Your question is a perfect example of what went wrong between us: you live atop a white charger bearing a red and gold banner. Instead of coming to the sensible conclusion that we're two different people who wanted different things, you feel compelled to bear the responsibility and blame.
The war is over, and you don't bear the responsibility of saving the world anymore. You don't bear the responsibility of saving me. The truth is, I grew tired of feeling like we were working at cross-purposes. I wanted to enjoy a social life and be around people; you wanted privacy and quiet, and you wanted to protect me to the point that I felt smothered.
I'm also not sure either of us ever truly reconciled our former House allegiances. In some ways, I think we embody our respective Houses to the point of stereotype, and you know what happened to Godric and Salazar.
The bottom line is, some things aren't meant to be, and you and I are one of those things.