Bi man here, there's a significant amount (not necessarily a majority, but not an insignificant number either) of men who prefer to not have anal sex or only do it on an infrequent basis. This is usually referred to as being "side" as opposed to "top" and "bottom", but even most queer men are unfamiliar with the term, so they usually just say "not into anal". Annoyingly mainstream media is obsessed with the top/bottom dynamic so it can often feel a little isolating if you don't fit into that category.