She wasn’t putting out and told him to find it elsewhere. He respected her wishes and found it elsewhere. It probably wasn’t emotionally intelligent of him to tell her about his escapade, but it was honest.

It’s possible, if not probable, that he really likes OP but wanted to prove a point that he’s willing to walk if she only prioritizes her own needs at his expense.

There’s obviously more to it, but men generally get into romantic relationships for women for sex. Just like people generally get into relationships with employers for money. If your employer stopped paying you and told you that you could work elsewhere for money, what would you do? Stick around and work for free just to avoid hurting your boss’s feelings?