Well, I relate this song to my personal story, because it fits it very well.
I had a boyfriend, but we were having many troubles, and then I met another guy. We became friends easily, and there was a lot of feeling between us. Finally, I broke up with my boyfriend because I didn't love him anymore, and I felt my heart so free, because I wasn't loving anyone.
But then I realized I was in love with this other guy, and I knew that he had been having a crush on me since several months. But in the moment he knew I liked him, he started acting completely different, as if we were almost strangers.
So, he "gave up before we started", because of his past. A girl before me left her boyfriend to be with him, and it didn't work. He thinks I've left my boyfriend because of him, and that's not true. "He hit a wall and tries to find a way around"
Long story, sorry if I bored you. And btw, I don't know if it is understandable, because I'm not english and my english is not perfect.