Theories + statement :|

Jaekyung is for sure in his suffering era.
To fans saying Jaekyung should kill himself, that is not a plausible answer for what he has done. Yes, he has hurt MANY MANY MANY people, including SWEET, SWEET, Kim Dan(who did not deserve AN OUNCE of the treatment he received). Jaekyung committing suicide is not something that does anyone any favors.
Jaekyung will be forced to learn from his mistakes, and have to pay the consequences for his actions, yes. Do I think he deserves Kim Dan? No, but author-nims current path is, of course, getting them together by the end. Jaekyung is gonna have to do A LOT of work to FIRST heal his own traumas(which are clearly there, since he is experiencing triggers from Junmin), but also try to make things right with all of the people he has wronged in his past and present, 100% including Kim Dan(sweetest angel).
As it can be seen, during his time of recovery he is being forced to confront his demons, which he is trying to evade by working out, insomnia(and headaches) not sleeping, and drinking himself into a stupor. He could be dealing with complex PTSD, which can be reflected in his insomnia and headaches(restlessness). Thus using Alcohol(and the "drugs" as well), works out, and watches films to distract himself(all subconsciously of course). Until he really sits down with himself and is able to confront his demons properly, he is unlikely to move forward. His "champion/ perfect" image has now been put into question, depending on his past, which has put him in a difficult position because this could make him look weak. This could also take into account that his possible trauma was either sexually related or bullying since his jinx is tied to that, which we are at the current time unaware of why he has his current jinx. He could be viewing his sexual partners as his past weaker self, and has he "dominates" them, that could "give" him the reassurance subconsciously that he is not his past weaker self, which in turn helps him in the ring, giving him the confidence needed.
The sum of his healing journey will probably conclude that he possibly no longer needs his jinx, since he will have worked through his traumas connected to his sense of weakness.

Anything I've stated above does not negate his behaviors, just putting that out there.
My apologies to those who do not agree, but Jaekyung committing suicide is just not something I agree with, but everyone is welcome to their own opinion. Just suicide is a serious matter, that should not be taken lightly.