“error in judgment”. I like that. I call what he did, sneering arrogance at the very least.
Did you ever bother with the facts?
He insisted on keeping out of questions regarding his girlfriend. The euro libs in the bank assured nothing would be wrong with it, if he signs her a pay raise (which she was entitled to anway). He trusted them. The trap snapped and the euro libs in the bank now can get rid of him.
If anything he was incredibly naive.