(Essay mode activated *boop*)
GermanyXBelarus..... interesting °_° I remember my dad said to me one, " Did you know Germany slept with Belarus." He was probably trying to reference something from history since he doesn't know that much on Hetalia. So...maybe a relationship between Germany and Belarus is compatible?
As for Germany and Belgium. I'm not entirely sure about that one. History wise they had a rivalry between each other during WW1 and 2, but then they both share an interest with baking.
I think I like GermanyXBelarus better. *Russia, your safe now~*