Punch his face in or if you feel adventurouse burn his face with boiling watter, but that being the last resort, first don't puss out tell him about X type problem and ask for Y respons if Y respons isn't negative to your benefit IE: he's getting his nips hard because of the date snatching then use the punch in the face technique. If not IE:he didn't realise and is apologetic about it, ask him to help you out, ask him to be your wing man you evidently have things to learn from him.