Would you let your man put his P In someone else ?

So me and my boyfriend have been together for a little over a year and he has been bringing up that he really wants to try anal. I however have no desire too try it and will not. We have talked about what if we get married and I still won’t do it. He says he really wants to try it and that its something he’s really turned on by. I told him that if he really wants to experience it that I give him permission to do it with somebody else who is into that type of thing. I do not feel like it is right for me too withhold a natural desire that my man has just because it’s not my thing. Am I crazy for saying that I would give him permission to do that with someone else? We would of course have guidelines. It would be a strictly anal thing no vaginal penetration. It could be a one time thing or if he really likes it it could be set up for it too be a continuous thing. Idk when I told my boyfriend about it he thought I was crazy but honestly I don’t think it’s that absurd. Please let me know what you think.