It is gossip and your floor manager really had no business translating that piece of information to you. She heard it from someone who heard it from someone. Does not make it very reliable. If this did happen, it still not your floor manager's business.

You talk to your boyfriend and ask him. If you believe what he tells you, then it is taken care of. If you do not believe him and want to talk to this other guy and that girl, ask him. Take care of this the right way, not by listening to someone else who was not even there.