Hello NotSure: So... personally I don't see any problem here with regard to your dating "M". She was with "J". They broke up when he got cold feet. Perhaps J should have thought twice before he ditched M. Now, all of a sudden, he finds out you & M are seeing each other. J wants M back & you're cast as an unfaithful friend. Oh, p-l-e-a-s-e!

From my perspective the one real potential problem here, as you clearly realize, could be that M might suddenly decide she prefers J & you'll be cast aside... at least until J gets cold feet yet again & decides to break it off a second time. To me, you don't owe J anything. If anything, he owes you an apology. But you do need to be mindful of the potential ongoing entanglements this situation could produce. And so the question becomes... do you care enough for M that you're willing to take the risk? Only you know the answer to that question.

I see this is your first post here on PC. So... welcome to PsychCentral! I hope you find the time you spend here to be of benefit.

May I suggest you introduce yourself over on PC's New Member Introductions forum? Here's a link:

https://forums.psychcentral.com/new-...introductions/

There's a lot of support that can be available here on PC. The more you post, & reply to other members' posts, the more a part of the community you will become. Plus there are the chat rooms where you'll be able to interact with other PC members in real time (once your first 5 posts have been reviewed & approved.) So please keep posting!