This seems to be so that the audience won't think the heroes are "queer".
The definition became more vague as language evolved. Note that the term "virgin" originally meant "a female who has not had sex with a man", and thus literally no male was ever a virgin - which sort of underscores the trope. Establishing the male lead's heterosexuality assures the majority of the audience that it is thusly safe for women to want him and men to want to be him. After all, while homosexual or bisexual characters are becoming more and more common, the number of them that are leading characters can probably be counted on one hand. It also, of course, serves to make the audience absolutely and totally sure that their hero is ardently heterosexual. We just have to be made aware that she is far from being the first beautiful woman he's had (Direct-to-DVD movies often get much lazier about this and combine it with the requisite sex scene, and will often have the male protagonist have sex with a few girls on screen while he's in the process of falling for the female protagonist). Generally, however, the more macho Action Heroes don't have wives or steady girlfriends when the adventure starts, because that would stop them from hooking up with the female lead. Don't Argue.Įstablishing the character's sexual competence varies from seeing a beautiful blonde, who has nothing to do with the plot and no lines to speak, crossing or leaving his bedroom early on in the film, to references to his ex-wife or old flames.
It doesn't matter whether sexual experience is in any way relevant to the skills needed in the plot, he just has to be Man Enough so he has to have Done It and preferably Do It Regularly. A guy who has never Done It, or even just does not Do It often, is simply Not Man Enough to save the day, solve the mystery or whatever.
While teenagers Can't Get Away with Nuthin', and characters in slasher films often suffer Death by Sex, it is understood that the leading male must be sexually active.