Gay threesome or no?

So I have been dating my boyfriend about three years now. Totally monotonous btw. Our sex life I think is great but I know he gets frustrated sometimes because I won't bottom as much as he does. I just really don't enjoy it as much as I should I think. Well recently we were talking and the idea of a threesome came up. At first the idea of us both getting to top and watch each other do it to someone else was somewhat exciting but the more I thought about it the more I wondered if this would ruin our relationship. I'm definitely a jealous type whenever someone hits on him but for some reason I feel like this would be kind of a hot fun experience for us. Does anyone out there have any advice on this? Anyone whose done this before and still managed to have a great relationship afterwards. He's been super supportive and understanding and I want to make him happy and experience new things with him but I'm kind of nervous this will hurt our relationship in some way. HELP?