Ron/Harry
I don't know. Probably because you were having a fight and you were being a git. And I don't think anyone wants to be proposed to in the middle of an argument. Maybe you should give yourselves time to settle in here? I mean, I really don't know, and all I can say is that you should ask her because you love her and want to share you life with her, not because it's the most romantic time you can think up.