I hate to admit this, but oftentimes I'm the world's worst boyfriend.
What do you do to earn such an "honor"?
I break a lot of promises to her
It's bad that you break promises to your partner, but it's encouraging that you realize that it's a bad thing. Now that you realize that you aren't always a good partner, you can work to improve and try to be the best partner that you can.
That would make her happy.
That's a good thing, right? Making her happy will make you happy. It's a constructive feedback loop.