What about marriage??

Does marriage really not mean anything to most people anymore? I am married to my high school/childhood boyfriend which we were on and off when we were younger but have been seriously together for over 8 years and married for almost 3. The thought of having kids and starting a family would have never crossed my mind before we had gotten married. It's really not just a piece a paper it's vowing yourself to the one you love and wanting to say in front of everyone that you mean forever in the relationship.

I know so many people who are planning having kids and getting pregnant without the thought of marriage or being together long enough to know someone well enough. This isn't aimed at people who get pregnant accidentally or aren't trying. I'm just wondering for the people who plan to have babies but don't plan out a long term relationship? I know it's the 20th century and I am 26 but I still don't understand when the sanctity of marriage got thrown out the window?