I think when you get together young, you grow together, at least in some cases.You ever buy a gun or a car that you thought was awesome at the time, only to find out "not so much" later on?
Yeah. There's no gun or car on earth more complicated than a woman. And 5 years after you buy the gun or car, it's still the same gun or car.
I married young, so I can't take credit for choosing well...I lucked out and accidentally chose a good one. But I have a couple of friends whose spouses flipped the crazy switch a couple of years in.
People change.