Yes.
Yes.
No.
No, but we don’t really get together much anymore so maybe that’s kind of cheating in answering this question. But that’s from having taken different paths in life and finding different interests, not from him and my ex dating. I still call him a friend without hesitation and would be there at the drop of a hat if needed. As to my ex, she and I are still very close and dear friends. We manage to get together semi-regularly and neither of our S/O’s, to my knowledge, mind.
It’s all good. I hope the best for them. There were concrete reasons she and I didn’t work out, they’re both good people in my eyes and deserve to be happy. If they can manage it together great, if not that’s ok too, I’ll still be here for both of them.
Just as an aside, I think two of the central reasons it works for me is I really just don’t do drama (life’s too short and there’s too much out there, I’d rather enjoy it than get worked up over it) and I understand fully and agree with why she and I don’t click that closely over the long term.