I think this song is about a guy being in love with a girl, but she wasn't first in his life, so she found someone who would put her first. Now the guy is still in love while she has moved on. When he says a that a heart don't break even, I think he means it's shattered. For example if you literally break a bone it can be a clean break which heals easily, but a shattered bone may never heal. This song reminds me of my first love, he was the first boy I ever kissed when I was 12 and he was 14, then we dated when I was 16 and he was 18 and he was the first guy I ever had s** with. Then when I was 26 and he was 28 we briefly got back together. After more than 10 years of not seeing him, I bumped into him last month and now I'm 37 and he's 39 (and a granpa!) and all those feelings came back. He broke my heart, and it did not break even!. Even though I am happily married and have 4 beautiful kids my heart never did completely heal.