Honesty, tolerance, and never forgetting the whole thing started because you are friends

Respect

I am waiting to see your thoughts @silvereyes

The 80 yrs old couple . Been together 60 yrs.said their secret was an arrangement they made at the beginning.
She made the minor decisions
He made the major decisions.
It worked they were still in love and you know in all those years they never had a single major decision
to make.

Time and separation...I am going out with so many people, but if they knew it, I think the relationship would stop. Nothing creepy about that....hehe

Fear of being alone?

passion compromise and effort

Common goals in what you want in a relationship. This is almost impossible to pin down because its different for every couple. Each person has things that are important to them. So one could say it comes down to relationship compatibility. This is not the same as shared interests. Someone who wants children being with someone who does not is going to always make a relationship difficult to maintain. Someone who has a high sex drive is likely not going to last long with someone who doesn't have one. People can change a bit but there are always limits.

A relationship is like a scale and everyones is different based on where they are in life, how badly they want a relationship etc. On each side is what is important to you that you can't budge much on that you have in common and on the other side is what is important to you that you don't have in common. Everyones scale has a different breaking point but once it breaks, the relationship is not a good one and will either be unhappily forced or ended.

If your scales are within tolerable levels you then must have your relationships future in common. If one values money gain as a primary goal at the expense of family and the other values family occassionally at the expense of money, its likely not going to last no matter how great it is at the begginging. Having the same or similar ending points is as important to the long term health of a relationship as compatibility.

Communication can be key to the future of the relationship as if you don't have the same future goals they are easier swayed early and entwined and compromised rather than after they have had time to settle and needs are not met.

Magic.....

Usually, I guess, but not for everyone (you don't need them all).........respect, loyalty, communication, trust, laughing and not being too uptight, finances, sex, and things in common like doing the same activities and liking the same music and movies etc.

Trust, friendship or just do as your told.

I don't think there is a golden rule. I have known several couples married for over 50 years and they have different reasons for the longevity. I also know a couple that was married three times and divorced twice. They had a set of ideas that were unique to themselves.

When I figure that out, I can disseminate that to the world. Otherwise, honesty, mutual trust, mutual respect, common ground, chemstry, communication, have always put me into the friendzone. In my opinion, that's the one to put your love into.

Great friendship and humor are important.

It came after the one before.

You asked two questions. What makes a relationship last and what makes them strong long-term? Long lasting relationships happen for many reasons, children, fear of being alone, financial reasons, fear of starting over, and some I'm sure I can't think of. I believe strong long-term relationships are based on being best friends.

Determination. Working through problems with respect. Choosing them over and over again.

Common interests,trust caring the same thing that make good allies . These are the things trumpie is trying to destroy with our allies and friends. He treats them like crap and then ask for their support. He must be a pure genius?

First, emotional stability for both is critical. Commonalities (mental, emotional and physical) are also very important but, in the end, it takes work on both sides. If one is trying and the other not it will not work.

I have been through failed intimate and friendly relationships. I have also been ones that have lasted. I hope I have learned something from both.

I think this differs with every relationship. Some factors for me would include (in no particular order):

A certain level of compatability in several areas
Physical
Some similar interests
Similar philosophy
Non-believer (I think being with a X-tian could work now that my kids are fully formed, but I'd still favor a non-believer)
Compromise (there has to be some)
Honesty
Communication

Human realtionships are complicated things, IMHO. This just scratches the surface. LOL!

Respect, chemistry, shared physical connections.

Communication, Unconditional Trust, Mutual respect and at least some interest in common.

Time.

No idea. I kept my last one going for 12 years by being a doormat and workhorse. Not doing that again.

Within the context of a romantic relationship, friendship.