Backstory. Met a someone on tinder (M45) at the end of January. We (me: F44) were both looking for very casual, and had not been dating long (him first date in 2 years, me first real date in a year) leading up to date we spent hours discussing sexual preferences and rules. Shared STI tests (for me it is a requirement on my tinder). On the first date we had sex. (Unprotected)

We continued to have a very casual relationship, with no expectations, I would classify as fuck buddies. We had dinner at his house 2x, but no further dates, just sex. Daily communication, after 9pm.

In scrolling the FB boards, his picture was posted. He was also seeing and having unprotected sex with another woman starting 2nd week of Feb. through end of Feb when she posted because he ended it.

When I confronted him, he understood why I was ending it, he said he had feelings and apologized. He asked to be friends. We spent 5 days talking non-stop.

5th day, he tells me, after I’ve somehow, stupidly developed some feelings, he slept with her again.

I’ve gone to get STI testing. I’ve told him I won’t sleep with him.

Here’s where advise is needed.

I’ve had successful ENM relationships in the past. There is a primary, but it seems all of this is too new to declare that. Right? He doesn’t have his stuff together. Also, part of what was appealing was the safety of monogamous unprotected sex. Protected sex can be hot, but there is also another element there that I have rarely explored.

All of my friends are saying run, but it seems I’m a Spanish bull, as I’m running towards the red flag. Please help.