We all know that Bruce Wayne spent years travelling the world, mastering all manner of esoteric mental and physical disciplines to become the Dark Knight. But there's no way he can do all that and be a bomb-arse lover, too. There is no doubt in my mind that Batman is very bad at The Sex.
He's the World's Greatest Detective and one of the most formidable multi-style combatants to ever walk the Earth. But the very fact that he's human means that Batman has to be bad at something. Traditionally, his weakness has been interpersonal relationships.
History has shown that team-ups are always rocky with the Caped Crusader. If he's right about something, he's a smug arse. If Superman or the partner in question trumps him, he sulks like a little punk. He's not been a great surrogate son or father either, what with all the gruff, aloof single-mindedness he foists on his crime-fighting. And if you can't relate to people, then you can't relate to your lovers.
Bruce Wayne has probably never gotten anybody off in his entire adult life.
Here's how Batman's initial sexual encounters probably go: Somewhere, deep under the ever-looping sequence of his parents' deaths, Bruce's libido explodes from being suppressed so long. He undoes the bio-metric locking mechanism on the utility belt, silently promising himself it's going to be different this time. Catwoman or whomever peels off that body armour, revealing the chiselled physique beneath.
(The weight of Batman's publishing history suggests that he's heterosexual, so let's just roll with that. It probably wouldn't be any different if he wasn't.) "Look at those obliques," thinks Selina to herself. "All those scars. This is gonna be hot as hell." Five minutes in, it's "what in the world is he doing with his pinky?! Is... is that a lock-picking technique? Jesus Christ, he has no idea what he's doing, does he?"
Bruce doesn't call the morning after. He'll blame everything on his mummy issues, if he ever admits anything went awry in the sack. He probably can't achieve climax unless his partner whispers Martha into the cowl's pointy ears. (Yeah, of course the mask and cowl stay on the whole time. "It... it's my true self.")
But wait, you say! The Dark Knight has come back from gruesome injuries and fought through the Scarecrow's fear gas with nothing more than his incredible will. Batman's got near-total control of his mind and body! The key word there is "near". Picture 20-something Bruce learning tantric meditation from some ancient yogi with a long, grey beard. He's already mastered the techniques to get his body to heal itself and make it so that thought and action are one.
You think he's sticking around so that he can learn to delay his own orgasm and have sex for six hours straight? Nah, son; he's got a plane to catch. If you're looking to become the black-cloaked embodiment of vengeance itself, sex-having isn't exactly a vital tool for winning the war on crime.
You know how Bruce is always pushing romantic interests away from him? "My mission doesn't allow room for attachments," he grunts. "The safety of Gotham City comes before anything," he'll growl. All of that is code for "Sorry I finished before you did." He gives Talia, Catwoman, and those other unlucky women the stiff arm because he doesn't want further confirmation that he's a five-pump chump.
Ultimately, Batman's a self-centred dude who couldn't let go of his trauma. He's saved Gotham and the world many times over, but pleasure is basically a foreign concept to him. If you want to nail a Bat-dude, get some of that trapeze action from Nightwing. He's actually experienced joy in his life and has a legendary arse to boot.