That's mawwiage. One day it's great, the next day it's very difficult.
So much patience is needed. Sometimes one mate speaks rudely and inconsiderately. It's hard to take the emotions that result from all the past traumas.
Singleness means going to sleep in peace whenever you want to. Marriage means going to sleep when your mate lets you!
Low expectations lead to more happiness. A mate can't fix all the problems from the past. A mate shouldn't expect a mindreader! Willingness to hold on through the hard times and always treating each other as each wants to be treated. And being too proud to apologize is really bad.
If you can't live without the person then get married. But just know that there's a lot of bad with the good.