Considering the amount of Aya and Cirno situations in the fanon (probably their dialogue at the end of Cirno's story in PoFV has something to do with it), this pairing does not seem to be one of the most unlikely. The pool is about expectations, right? Besides, when it comes to canon, most of those pairings aren't that likely, anyway.
dooon't~ even♪Cirno-sa...Cirno...Uuu, I'm still no good at this...Ghk-....The Endblushhhh...mwii~nIt's okay, I'll make sure ya don't get tooooo cold!huggggg~(It's so hot...)Hu~ hu~ hu~
A~ya~♪mwii~nEhhhh...?Y-you know, I think I'm fine n-Ch-...Don't say such things so suddenly...