The attraction/repelling can be on a case to case basis, yes. It's also fine for a character to not react to certain other characters while still attracting/repelling others. And the sandwiching of characters, with two repelling characters mutually being attached to one attracting character is also super fine.

Truly, this event is just about getting a little silly and putting your characters into situations that could be awkward/embarrassing/funny, so pretty much anything goes.