It is the favorite fantasy of many husbands, if not MOST of them, to watch other men fuck their wives. Most will not admit it, especially to their wives, but it seems to be hard-wired into the male psychosexual psyche to want to share their wives with other men, in whatever way they can.
It seems completely un-natural for a man to expect to have exclusve rights to any woman's pussy, even if he is married to her. By the very basis of how males and females are able to perform, it is unreasonable. A woman can give as many fucks as there is time, and as there are men available. But a man is limited by his "recovery" time, before he can fuck again.
It seems perfectly reasonable that a woman should have at least two men who are giving her as much sexual attention as they can. If they would take turns fucking her, preferrably in front of each other, then they could perform for much longer, together, of course, and the woman/wife would come a lot closer to getting the quantity of fucking that she needs.
I will say it again: Pussies are to be shared! Your wife's pussy! My wife's pussy! All pussies, everywhere! Let's share those married pussies with other guys!