My best guess is that he is already dead (suicide by cutting) and was a ghost or invading her dreams, and refused to try to get her to do the same since he is in love with her.
@butterfwee Maybe the girl asked the guy (or vice versa) to commit suicide together, and when they tried it, only one of them actually ended up dying, and so he comes to her in dreams to convince her to "complete" the pact (but loves her too much, and realises he made a mistake)? Could be entirely wrong, but that's my best guess.