Break up with him

You decide you want her yourself. Seeing her with someone else would probably break your heart so you quickly write him that you're really sorry, but since you are into somebody else you can't go out with him. He asks if you're joking but you tell him that you're honest. You say that you just wanted to not make him feel sad. He then writes that you're a bitch and that he never wants to talk with you again. You then see that he blocked you. Harley would have felt bad about this, but you didn't really care, what passed on to her. Thanks to your actions she didn't care about this idiot anymore. You also see that she did not write anybody about it.

With this dude out of the way...