1.The sister was in love. Love turns people blind and yes, she definitely was thinking he could “change him”. (She still homofobic tho, i get the hate for that)
2. The uke is nuts. He saw his “lover” was really close to his sister and was backing down because of it and didn’t like that so he plans this sick environment where the plan is making the sister hate her brother so that he could have all of the seme just to himself.
3. The fact the uke assault seme while married to the sister In my view, they really only had sex after the divorce, while before, when the uke and the sister was married, was only assault (“oh, but i think the seme didn’t mind it at all” still bro, look the painel where he was sleeping)
4. It’s not common seeing uke who are nuts, not the seme, so, in some way, it’s new
you reap what you sow