Technically Itae hasn't done anything wrong, with or too Jinwoo, but he definitely feels like the wrong person for Jinwoo. I like Itae as a character but he needs someone who matches his energy. It's pretty obvious that Sehyun is the one Jinwoo will end up with. I'm hoping the creator will have Itae meet someone a little more his style.
I'm guessing with the amount of pills he been on since he presented as a Omega at least one of them acts as a birth control. Or he's possibly infertile because of it.