Some couples, in Hollywood or the "real" world, are meant to be together.
On the flip side, other pairings simply make no darn sense whatsoever.
As celebrity gossip publications love to say, stars are JUST like us, and that means at times being attracted to the wrong people, or at least unlikely ones.
Here are 17 cases where that was undeniably true ...
Ashton Kutcher and Demi Moore shocked the world when they went public with their relationship. They shocked us even further by discussing their very interesting and involved family dynamics with her ex Bruce Willis.
Jessica Simpson and John Mayer actually look great together, but she's way not cerebral enough for him. He once said she was addictive, like "crack cocaine."
The ultimate in WTF, Lady Gaga and Taylor Kinney seem like complete opposites, but if opposites really DO attract then maybe that explains this totally weird coupling.
Now THIS is a weird May-December romance that kind of grosses us out. (At least Courtney Stodden has that whole "attention whore" thing going for her...) Mary-Kate Olsen is engaged to Olivier Sarkozy which just SCREAMS "Daddy Issues."
It's just human nature sometimes. We can totally relate.
Who's to say what attracts people to each other? Primal instinct? Money? Fame? Whatever it is, when you're fixated on someone, no one can stop it.
Inexplicable romantic urges are as old as time, and not unique to celebrity culture, but you do wonder if any of these duos would connect as non-celebs.
Rihanna and Leonardo DiCaprio make for perhaps the most obvious, recent example. No way those two are actually dating, we thought. We were wrong.
Of course, some seemingly unorthodox pairings go on to prove us wrong. Whatever you think of Kim Kardashian and Kanye West, they make it work.
When those two got together, we were as skeptical as anyone, despite their mutual adoration for themselves, their looks, and doing anything to get attention.
Now, they're married with a little girl. They clearly love each other as much as they love to tweet photos of Kim Kardashian nude. Who are we to judge?!
Others aren't so lucky or long-lasting. Some of the relationships we've seen come and go are pretty bizarre, and not just because of things like age differences.
Scratch your heads along with us in the gallery above.