That would be a problem inside your marriage with honest communication without fear of judgement or embarrassment. So unless you can get past that you are up against it. Sharing your wife takes the utmost honesty and communication between the husband and wife. If you can get to that point, your marriage will be better for it. I have had friends who have had all sorts of strange fantasies and told their wives. Not one of those wives got angry. They either said they could accomodate it, or they couldn’t. So my advice is to be completely honest and up front. It won’t hurt your marriage at all.