In Love With My Best Friend

What do you do when you fall in love with your best friend? Which also happens to be your band mate and also happens to be in a serious relationship? Well when Harry and Zayn start to develop feelings for their friends, which both have girlfriends, what are they going to do? [BoyxBoy]- If you don't like that type of thing, you can still read it because I will warn you and it's not completely about that! :)