The girl did broke up with the dude 3 years ago (3 MF YEARS), so if both parties (i.e magician dude and pink haired girl) don’t find the whole deal icky(?, I think it’s fair game.
Also if she wants to break up whatever relationship she’s in for whatever reason, she can absolutely do that, like wtf people??
And if the white haired guy states to the involved partner that it’s a casual thing, it’s also fair game