how do you get over someone you love so much?

My boyfriend and I have had a rough year together, and it only feels like things are getting worst! We argue about everything little thing, and always tell each other we're better off single, but when one of us try leaving we always end up back together. He's done some things in the past behind my back, but has never cheated and every time I'm alone I think to myself saying "I know he's not being faithful to me" but there's something holding me back. Any advice on getting over him faster, and less painful?