Calum: You're dating Michael. You knew Calum had always sort-of had a crush on you, but you didn't know he loved you. And yo liked him once upon a time, but then Michael came along and swooped you off your feet. And now it was too late for Calum to come back around.
Michael: The distance would ruin it. Because Michael is always touring, it meant that he would have no time to spend with you because you could't afford to fly out at every opportunity and he couldn't just fly back and forth for the odd day. It sucked because you were great together
Ashton: You were friends with benefits. And you both promised feelings would be the last thing you wanted to happen. But somewhere along the line, Ashton fell for you and didn't have the nerve to tell you that he wanted a relationship to be a new benefit.
Luke: You don't love him back. Luke's always been your friend. Just that. And any idea of taking it further just seemed ridiculous to you. And when Luke suggested it one day as a "joke", you laughed so hard at the idea and so did he. But you actually broke his heart.