Yes, Christianity, for example, just stuck its nose in and found it as extra way to 1) get in more members, etc, 2) to make more money from the marriage rituals, etc, and, 3) Governments got involved, in my opinion, JUST for the money to made as well.
In Ancient Egypt, for example, there WERE NO, what we would call, marriage ceremonies/rituals, instead should a couple wish to 'unify' as a family unit ALL they need do was to spend 3 or more nights together in the same house, sharing the same sleeping arrangements and they considered, after that, to be the foundations of a new family unit.
I see that and in my own opinion, SHOULD 2 people decide to want to live together as one, then that is their decision and theirs alone, a Marriage Certificate, in my opinion, IS just a piece of paper that presumes to license 2 people to do the same thing as, mostly, have done well before undertaking the Arcane, Archaic and meaningless ritual of standing in Church or Registry Office, etc.

@Triphid Mmm I agree in theory, well and practice personally. But the wedding licence gives the partnership extra rights when it comes to: medical advice, if one person is e.g. in a coma or mentally unsound for decision making and also the property rights and legacy rights can change I think. Quite a few people seem to prefer a legal marriage just so that they all have the same last name legally. Maybe it depends on the Country?

@girlwithsmiles Well thankfully, Australia has advanced beyond England these days and de-facto partners, either hetero or same sex, are now given the same rights, etc, as those under the archaic Religious Marriage Licensed ones.

And now, who told you all that? Can you name any of the adults who shaped your thinking? And where did they get their ideas?

@Jacar other than having parents who were a living example every day of the importance of living up to one's word in all things, nobody told me any of that. This is what experience has taught me.

Well said!

"Promise" is the operative word.... Is this explicit, overt, historical,... Why do you think that sexual activity is sacrosanct? From whom do derive this conclusion?

@Jacar any time you betray someone on any level, especially someone to whom you have pledged to be trustworthy, you are a crap person. Once you have betrayed trust, you do not deserve to be trusted by anyone again. This is not complicated at all.

@Deb57 You assume a promise was explicitly made, and understood by both parties.

Most of us visiting this site are non-believers. We are challenged from the theists as not having a moral base. My question is about what we can point to as our the foundation of our moral responses, and feelings, and thought.

Mostly you have written about the end result of those foundations. And as important as they are, how we respond does not explain why we do so, and why and where from and how deep, those very appropriate respones exist in our individual lives.

I maintain that few humans ever explore why the respond/feel the way they do. That is my interest here and now.

@Jacar I didn't "assume" the promise was made, I literally participated in the exchange of promises, which is what my wedding was. What was expected from one another regarding fidelity was made explicitly clear well before the wedding. If any of it had not been something my partner was comfortable with agreeing to, he had ample time and opportunity to discuss it or back out of the partnership entirely. I certainly wish, now, that he had done so, since he was not honest with me from the beginning about his pattern of infidelity. If sexual interaction with people outside the marriage is something that has been agreed upon by both partners, then it is not infidelity or cheating. Betrayal is immoral regardless of what parameters have been drawn in the beginning to determine what behavior that entails. There aren't really any shades of gray there.
Morality is not synonymous with religion. Morality has nothing to do with religion, really, since most people tend to be far more moral than the gods they claim to worship. Morality stems from treating others in the same manner in which we, ourselves, hope to be treated. Sometimes morality is just not treating others in a way we would not want to be treated. Fairly interchangable, I suppose, but religion of any kind is not required for either. It's a survival mechanism that even non-humans frequently apply to their behavior. By the time people reach middle age, most have had enough experiences, or have watched and learned enough, that they have drawn their own conclusions as to what they consider moral. There may be some who adhere to the idea that they can't be moral without their religion, but that just hinges on one's ability to think critically. This does not mean they always act in what they consider a moral way.

@Jacar any promise: (i will pick you up at 8, I will cosign a loan for you, I will help you pick out a new house/shoes/hairstyle) either implies or overtly causes the promisEE to make plans dependent on the actions of the promiser. Why are you dragging in sexual promises as if they are any different? Why drag in "morality"? If you cause another to rely on your performance because of you very own words to them and renege, you are a piece of crap! Period!

@Jacar I never think about " morality" I think about kindness, keeping promises, the Golden Rule. Applies equally to "meet you at 8" and ripping kids from parents's arms because "non-white"

I love this answer

Yes. Thanks.

A very valid reference. I am all with you about this. I find the morality here as occurring the possibility of passing disease to others. To do that knowingly would be deeply immoral.

@Jacar absolutely agree. Immorality is exposing others to disease & lying about it. If it’s an open relationship, say so. If you care enough about someone enough to share your bed, be honest. Your lover should be given a choice. If he or she declines non-monogamy, respect that. Open relationship is fine, if honest. Otherwise, you cause harm. That is worse than « cheating ». It’s called « lying »

This

Based upon what? Why do consider sexual activity to be different from all other of a spouses behaviors?

@Jacar Sexual activity is reserved for one person alone -- one's spouse. Cheating on one's spouse by having sex with someone else would devastate the spouse. To keep my spouse happy, I do NOT have sex outside of my marriage.

@BestWithoutGods . . .Your conclusions are reasonable. But, who told you that? And why did you still believe them?

Did any of your vows/pre-partnership conversations include actual agreement about sexual activies? Having a meal with others? Sharing a movie,.... with another human being?

Why is Sexual activity so special?

@Jacar Yes, the marriage vows include sexual faithfulness. Unfaithfulness causes marriages to fall apart. I have seen many divorces caused by marital unfaithfulness.

I have no problem with a spouse eating a meal or seeing a movie with other people, as long as it is not one-on-one like a date, and as long as there is no romantic tone to it. My spouse has a bridge partner. They play bridge together twice a week. That's fine with me. It is a group activity where hanky-panky would not occur. But if they were to have sex together, our union may very well fall apart.

When I was unmarried, I went through a free sex phase. Each time I moved on to another lover, the prior lover would be devastated. The whole free sex thing caused more pain than pleasure. Therefore, I grew out of it, and decided to be a faithful lover for the rest of my life. For the last decade and a half, I have had sex with one person only -- my spouse. I no longer cause anyone pain, and that makes me happy.

@Jacar the question is, after tons of posts saying a promise of any kind should be honored, why are You dragging "sexual" into a special category??? It is just another promise that should be kept!

@Jacar ummm, disease? And/or betrayal?

That is one of the bits i am trying to explore. What are morals? These are tenets that societies agree upon to ensure the survival of the tribe. And then, how are they displayed. Good manners is one of those displays.

@Jacar Ethics/morality vary from culture to culture and age to age. They are part of the social contract.
Good manners is to adhere to that social contract.

The individual knows their own ethical/moral values and so to question the validity of the contract is to attempt to justify a negation of responsibility within the social structure.

It is religious based in our society. Hence by suggestion.

@Jacar Are all marriages religious in your country? What do non religious people do if they wish to marry? Marriage in some form or another predates Christianity, it’s just that they have turned it into a sacrament. It’s a contract between two people regardless of religion.

Interesting conclusions. But who told you that, and why do you accept it all?

@Jacar Who? More of a "what" really. The disease vectors can be demonstrated with a simple flow chart. Rationale can show how when you trust someone and they betray you and you detect that betrayal, then trust diminishes. Trust is integral to security. Security lends itself to quality of life. These thoughts may not have originated with me but cause and effect have solidified their validity.

It should not matter whether or not humans are intrinsically monogamous or not. As far as you have cognitive abilities of an adult human, you should be able to commit to whatever sexual arrangement you take up.

'Don't do to others what you don't want done to you'.

That is a good start. Yet, that does not explain why sexual activity is treated differently than most other human behaviors. At least in the west.

Islam's suppression of women goes far beyond just sharing ones sexual bits.

@Jacar In what way is sexual activity treated differently than other human behaviours in the west?
Islam is oppressive like any other patriarchal system.

Good. But;;;; where did those ideas come from for you? and why is sex considered to different than all other human activities that are not considered to be exclusive?

@Jacar who said anything about sex? You can be cheated on emotionally, and trust me that is just as bad if not worse. I was raised that when you gave someone your word, you honored it.

Ahhh, the old "we don't have a fucking clue" argument.

And. Good points. This issue is complicated. My question: how do you feel about these topics, and to what do you attribute to as the foundations of those feelings?

Raised very strict mormon. When I was breaking with religion I very closely examined those things I thought were my core beliefs. Turns out many of them were based on the opinions of dishonest men trying to control others.
I base as many of my opinions as I can on observation, research, and the golden question. I don't want to be cheated on because it hurts like hell, so I don't cheat. However, people with the right personality can enjoy multiple meaningful, honest, and intimate relationships simultaneously, in my opinion.
Monogamy is neither outdated nor THE correct answer.
After I discovered my spouse's infidelity I tried non monogamy ethically for a while. It was fun and the energy from a new relationship is its own kind of high. Jealousy is always an issue, but can be dealt with by honest reflection, good communication, and caring partners.
I could do either, depending on who im with.

"Promise" when, in what context? Wedding ceremony? religion? Before marriage?

@Jacar At any point in the relationship. People should have conversations about what they expect from their partner, and not simply assume that monogamy is a given.

I don't believe in marriage.

@KKGator Marriage is good for legal reasons: custody, property control,.... Unfortunately, too much of the marital law is all about "betrayal."

@Jacar The things you cited as reasons for marriage being "good", can all be satisfied through other legal contracts.
Marriage is unnecessary.

@KKGator Yes. But is mostly the accepted vehicle.

@Jacar Slavery used to be the "most accepted" vehicle for getting one's crops out of the field, too.

The old systems change when we no longer agree to accept them.
Just because marriage has been around for almost as long as humanity,
doesn't mean it's days shouldn't be numbered.
It started out as a property exchange, even before religion got its ugly hands on it.
Just another example of how religion corrupts everything it touches.
No matter how mainstream it has become, marriage is an antiquated and useless system.

So where did the father get his thoughts?

@Jacar From his father before him and those before him as well, ALL were Atheists to the core and VERY Ethical and Moral people with a very deep seated Community sense of Conscience and caring for others.