I'm sure the lover didn't and won't accept that second person involved. He's a piece of shit that wants to have it all without caring about his lover and the male lead's feelings. And he's trying to guilt trip the male lead, that wants to cut any relation to him.
The difference between polyamory and two-timing... One is consensual and considered ethical while the other one is just douchebaggery ┑( ̄Д  ̄)┍
On the other hand Mafia Daddy is just