How to ask a guy to Sadies?!?!?

So me and this guy have been talking for about 2 months we have had a thing but for family sake we agreed to just "be friends" haha i really want to ask him but he has some girl friends and idk if they want to ask him! he is soo atractive and i really truly still like him! How should i ask if i should even ask him at all! the dance is next week so help me asap! :) thanks