If the uke was seriously cheating, of course that would have been a major red flag. It is obvious though that he had always been that way- perhaps even from before he started dating the seme. The seme still accepted him and decided to go out with him, cheating habits and all. It's clear that the uke's behavior is a sort of play for them, rather than an issue. I think that's what makes this BL unique.
If the uke was seriously cheating, of course that would have been a major red flag. It is obvious though that he had always been that way- perhaps even from before he started dating the seme. The seme still accepted him and decided to go out with him, cheating habits and all. It's clear that the uke's behavior is a sort of play for them, rather than an issue. I think that's what makes this BL unique.