I know a manga where it's like that, but the guy is pretty insane and the girl is confused on how to handle it. She moved on with her life but he didn't know if they were still together. When she finally told him that they were over he went insane and thought that only he would be able to have her. It isn't a murderous insane or anything like that, more like delusional.
haha I'm 4 years late to this comment, but would you mind sharing the manga title?
Dude if it were still 2017 I would let you know but it’s been forever lol
You know what would have made the manga good? When she figured out that he was using her, she should have gotten mad and cut ties with him. Then the guy would have realized that he truly did like/love her and then HE would have chased after HER. So tired of seeing female characters chase after guys when it's the guys who do them dirty. It just portrays girls as these weak creatures. Amazing art though.