I lean towards Zoid's ^^^ thinking. He sounds like the type that would pay little attention to his girlfriend and could get an early attitude (either to push even further or sourer resentment) if it was whispered from the host. The best option may be to explain to a guy he 'gets along with' that some other less open people have been insulted in the past and while you want him and everybody to have a good time, you don't want him take the lead this time. Ask them to please mention to him it "early", at arrival.

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