I think the main problem is that ppl are thinking of who is better for Ian instead of who Ian really wants. TJ is never an seen as an abuser to me. The one time he fucked up was breaking Ian's leg unintentionally and indirectly. Even tried to apologize to Ian but Ian stopped him. But he also did his best to keep Ian safe from the very start, as selfish as his intentions are.
All 3 have their issues and are not saint. TJ with his dumbass blond self to unable see that he loves Ian, Ian being wishy washy and also not being true to his heart and outright tell TJ why he wants him, and Jo being selfish ( because stopping Ian from going to TJ during the first fight was pretty much more for himself rather than for Ian ) and obsessive over someone he barely met.

I mean obviously TJ wasn't the RIGHT choice, but I understand the reason behind it. I don't support it, I just understand. ╥﹏╥
There are so many victims that can't get rid of their attachment to their abuser. It doesn't help that they have shared trauma as well. Even if he COULD move on from TJ to someone else, a baby simpleton wasn't gonna be enough to fill that void. (Sorry Joe, we love you)
Anyway I didn't LOVE the ending, but it was still enjoyable. 4/5