[Stefan always has something to feel guilty about. It's his shtick. But he doesn't say so, because guilt is something he tries to hide, bury deep, and forget about.
The last part is the one he's never managed to do.]
I know you didn't. I'll be here for you either way.
[If she's not going to choose him, he'd rather it happen now before he falls to deeply. He doesn't think he can take that again.]