I'm sure the sex is fine, It's that it's like a bad movie with great effects. It looks appealing, and you might enjoy a moment or two, but you don't really care about the people involved, so it doesn't really satisfy you.

I know I know, " muh capeshit," but it's the best example I can think of. Compare the first Avengers movie to the Tom cruise Mummy Abomination.

The characters in the avengers have already been set up, so you're already invested in them to some degree or another, and the action scenes are reasonably well paced, and the slow points take the time they need without dragging things out. Far from perfect, but entertaining and you enjoy watching it. This is essentially what a good relationship is like. You actually care about the other person, so you're trying to please them as well as yourself. The emotional fulfillment is better than the sex.

With the Mummy movie, the effects are pretty good, the sets are impressive, but the action is stale, the characters are barely set up when they're actually set up, and by the end of it, you're disappointed when the main character doesn't die at the end, and not just because he's played by Tom cruise. This is your one night stand, an excuse to cut to the exciting stuff with no real appreciation or caring for anyone but yourself and what you can get out of it.