My ex did this with his friend he had slept with too. Notice I say ex. He would even go as far as to say nasty things about her and that he wasn’t friends with her anymore. I found out that apparently she was embarrassed enough about sleeping with him that she would say he didn’t count. He doesn’t know this but it definitely made him look more pathetic to me since he seemed happy (?) about it. Shortly after we broke up, he went back to hanging out with her even though she was really just hooking up with his best friend in their new apartment while he was there. It sucks because you want to win over their attention the most for whatever reason but it doesn’t work. I don’t think it’s sustainable, I’m sorry this is happening.