Fantasy: Your wife will be your life partner, like a friend you will have great sex with all the time, do cool stuff with each other, have great conversations, have a family, etc.

Reality: Your wife quickly turns in a bitter cunt who controls your entire life, her looks go downhill fast and she becomes a landwhale, she fucks other men on the side instead of you and starts resenting you because you're not longer an exciting novelty, divorces you and ruins your financially, gets the house you worked and paid for and you can't even see your kids anymore because the court believes her lies over anything you say