arkie, I understand what you're going through.
I don't know which one of my friends decided I was "safe" enough to play with, but she was the one afterward who dared he and I to play together. It kinda backfired, as he found he really liked being with me as much as her. (I don't know if it was because I was his first MM?) I know there was some discussion to bring her girlfriend in, but I never found out if they did accomplish that. I even asked about my gf at one time, but they didn't click.
Even though it was an occasional thing, she called it quits after a couple years. He and I fooled around maybe half-dozen times over the next few years, but she got paranoid over it, thinking we were messing around every time we went out. I actually turned him down a number of times.
There were some other issues between them I was not fully aware of, and we eventually ended the relationship, for the most part. There's still the occasional email and an ongoing legal matter of mine he was witness to, but otherwise we never see each other, anymore after 17-18 years.
I still consider him my best friend, but I know she comes first in his life.