There is a subset of straight men who are extremely fragile and think that they can only authenticate themselves by acting like something out of a Rambo movie. It's insecurity. Many of them also can't be in a relationship with a woman unless they make sure that she, and the whole world, knows that he dominates her. They are uncomfortable in their own skin, so the Tarzan/Rambo bit provides the fantasy bit that allows them to survive. They pursue and marry women much younger than they are, too, because they are not grown-up enough to maintain a relationship with an adult woman.