Threesomes

My boyfriend wants to have threesomes, we've both done them before but not since we've been together. I love him and honestly I think he may be he one I want to stay with. I'm not comfortable doing them, because I'm honestly very jealous. He says that he wants it because it's a variety, but I feel that it means I'm not giving him all he wants. Should I be worried, should I allow the threesomes?