
Uke was originally a beta. They may have been dating for a while, but changing into an omega would more likely strengthen the relationship, so there was no reason for him to hide it. How much do you want to bet that night was his first heat? Then he got dumped the very next day so obviously he wasn’t going to stick around. Seem didn’t care about getting answers, figuring out the “betrayal”, being involved in his kid’s life, nothing. He was pissy that something happened that was beyond his control, so he decided he would get even by assaulting Noah, treating like a sex toy, turning his life upside down, all without any regard for the well being of his child (who he wants full custody of solely to spite Noah).

It most likely was his first heat... Even if it weren't he's pretty clueless not to use protection.
What I'm curious about is why DoYoon broke up with him.
And yes, why did it take 5 years?!? When clearly he could have found him sooner?!? Did YeJun do SuCH a good job of hiding that he couldn't be found?!?
But even if it were his first heat, wouldn't he have know he's turned into an omega?!? Usually omega good doesn't involve going into heat right off the bat. I mean...I'm sure he must've noticed his body changing....
You know what pisses me off most is the alpha seme coming to uke omega after 5 yrs even after knowing he's his mate and with his child and still has the audacity to act like shit after all that !!!