Such a dark betrayal, to leave parsee for suika on Christmas Eve no less

What betrayal? Yuugi and Suika are friends. Yuugi and Parsee are not. They've never even seen each other before.

There is a world outside the ingame stages. They live near each other, so it is reasonable to assume that they met at some point in time.

There's a good chance Suika didn't even know who Parsee is, and is probably going to be...maybe a little embarrassed when Yuugi tells her.

Then they make up. With alcohol. Lots and lots of it.