A lot of guys are uncomfortable with the social dynamics of parties. A lot of this is due simply to ignorance. Ordinarily I would simply suggest removing the source of the disagreement for the sake of the relationship. But since it’s your job and you make money with it and you find it fun, I’d suggest a different approach.
Take him to the parties with you, make him the star of the night. Maybe do it first on a day when you’re not working so it doesn’t interfere with what they’re paying you for. Get him feeling good about being at the party. Encourage him to go dance with other girls. Ask him about his experiences and let him know it’s ok.
When he gets into the spirit of it, dance with a few guys. Be cautious and don’t go too far with it. Keep an eye on him and stop if it’s looking like he’s feeling jealous. Ask him if he’s ok.
Between the atmosphere of the party, the attention you’re giving him, the attention he’s getting from other girls, he’ll eventually loosen up. He’ll realize that nothing’s really going on and it’s all just a bit of fun. Whenever guys do stupid things to try to get with you, share the stories with him and laugh about them together. He’ll come around.
If you see him getting too frisky with a girl, just tap him on the shoulder and interrupt whatever they’re doing. Parties are weird for guys who aren’t used to them. But if you start seeing a pattern, definitely have a conversation about it.