
Terrible ML for jerking him around but also… the ML isn’t cheating? He’s in an open relationship and everyone within that relationship is a consenting adult where all of the partners are aware of each other and even get along. That’s kind of polyamory but I guess they don’t really have that term in Japan? (Though people in poly relationships don’t look at their partners as accessories so that part is wrong. So it’s like… halfway to a poly relationship)
But yeah, it’s absolutely terrible of him to keep hurting the one he claims to love the most.