Married for almost 9 years here with one baby.... Here are my thoughts....
Marriage is not for everyone! Contrary to what society tells you, some people just don't have it in them, or they at least don't want to be in a situation where they don't put themselves First, because that's honestly an important aspect, it's not always about you in marriage! I'm not saying you have to be a door mat being walked all over, but you will have to compromise from time to time.
Some people like the comfort of having someone there for them, they like the stability of not having to go out and chase tail, and are just happy with a stable life. Works for some people, not for everybody!