Disney may own Marvel these days, but graphic Marvel sex still has a whole history that would make Walt blush...or possibly claw his eyes out. It only makes sense that if superheroes with perfect physiques existed, they'd have sex with each other, and Marvel's whole thing is that it deals with real-life problems for its characters.
Sex causes problems, true, but the way sex scenes in Marvel comics depict doing the nasty sometimes is a problem in itself, often playing intimacy for shock value, or creating what is effectively licensed fan fiction. The reader, in the end, must be the judge.
Here are the most particularly vivid scenes of graphic Marvel sex. Be forewarned: not all are consensual, and even those that are can get unpleasant in other ways and may be NSFW.
Tony Stark and Black Widow Make a Sex Tape
Okay, to be fair, they didn't intend to make a sex tape. The security system was hacked. But that's not the disturbing part.
The disturbing part is that Natasha appears not to have nipples. No wonder she betrayed the team - Tony probably pointed that fact out and it made her angry, or something. Hey, that makes as much sense as anything else in The Ultimates.
Ant-Man IN the Wasp
While everyone wonders about certain superheroes in the sack (stretchy Mr. Fantastic, for example), Hank Pym actually went there, using his shrinking powers to go all the way inside girlfriend Janet Van Dyne, before coming out dripping with moisture. Because Avengers #71 got a rare "mature" rating as a result, there was some controversy, but fans complained just as much about the overall artwork and story as they did about excess Wasp-juice.
Now that Disney owns Marvel, and Ant-Man's a family-friendly movie character (and not even Hank Pym any more), he'll presumably stay much drier.
Deadpool Does It in a Coffin
This one might be the most normal one on the list. Just a married man having sexual intercourse with his wife.
Except he's an immortal tumor mutant, she's a shape-shifting monster, and they're doing it in a coffin after she just punched a hole through another guy's chest.
At least in the movie, Ryan Reynolds's sex scenes all happened pre-mutation.
Wolverine and Magneto's Wife
In the Ultimate universe, Magneto had a wife conveniently named Magda, but before they were married, she took in an injured Wolverine and they engaged in a little coitus interruptus, casting some doubt later on the true parentage of Scarlet Witch and Quicksilver.
It gets better, in a terrible way: Quicksilver and Scarlet Witch in this universe are into incest... and Wolverine spies on them doing it. Sometimes he's actually the worst there is at what he does.