What is marriage to you all anyway? A state of closeness, or just a way of being sure to keep your parner as you have it all written down on paper? I'd never EVER marry anyone for the purpose of making them stay with me and not cheat on me with everyone else. I'd boot a girl like that out ever so quickly.
Personally, I've just never seen a need to marry anyone if there's enough trust involved in the first place.
It is romantic, and if you are with a woman for 10 years and you arent married and have kids and are like... this is my girlfriend and our 6year old son, its weird. People are pushed into getting married, and I am fine with it