i think the seme forgot because of some sort post trauma experience. something like "what did i just do? i dont want to remember this" i mean i sure when they're small he like the mc too. but hearing that the MC's dad is the cause of his dad suicice it must have been quite a shock for kid at that age. And he need someone to blame, too bad he leashed out on his loved one.
being gay is a blessing (๑•ㅂ•)و✧