I feel more sorry for kurumi chan than any boy that has her as a girlfriend. She doesn't exactly hide her possessiveness so you should know what you're getting into when you get into a relationship with her right? I'm not saying her behavior is spotless though
I personally think it would be interesting if there was no reconciliation or happy ending that involves the two of them but these kinds of mangas always have that theme in them. Of course, just because I would find it more interesting if there was no happy end doesn't mean I'm not gonna keep...