I have often said, on various sites, cheating is not the sex, but the lie.
As a young bisexual male, those many years ago, I had a relationship with one of my male friends for about three years before the subject of marriage with my girlfriend came up.
We had a quite lengthy discussion one night about him, and that i would hope to continue, but, needed her permission and understanding or I would not burden her with it.
background, both she and I are the oldest of 7 and 6 siblings and both have been very sexually active up to this point. So, was the resolution to have "friends on the side," and continue with those friends, tho , and we agreed to try it...we were 53 years. We had friends, we had sex, precious, protected, and safe sex.
Never talked about what we did, never judged, never embarrassed, nor humiliated the other, BUT MOST ESPECIALLY WE NEVER LIED TO EACH OTHER...seems to me that sex is not nearly the destroyer of trust, but is the lie...
Just a bit of food for thought, catagory.
Some can agree to this and some cannot. I have been the victim of adultery and lying and I cannot subscribe to this lifestyle. To me sexual infidelity (in fact anything that can lead to falsehood- gambling, drugs and on) also leads to a phony relationship.
We were always open but didn't have sex with anybody else for 20+ years, we wanted to focus on childraising. I've always had very intimate friendships and my first wife was Aunt Alice to my kids and friends with my second wife. My wife says I'm the most faithful man she's ever known, which is true on two levels. I didn't make a promise I wasn't ready to keep and on a practical level I'm better at monogamy than many people who "swear before god to cleave only unto you" (especially compared to her fundamentalist family)
My husband and I started out as a monogamous couple but shifted into polyamory several years ago. Honesty and communication are key!!
It seems like semantics. Sex is physically intimate.
There is also the issue of lying.