Something Existing

It's been 8 months I live here and graduatelly, I realized more and more things here. And most of them, I do not understand why they would choose to do this.

Most of people here choose NOT to get married but they live together, rent the place together, or even they but a house together. And yes, they do not get married, no wedding, no shit but yes, they have kids together, of course. It's a little bit hard to imagine the reason why they do it like this. To avoid the heavy responsibility? To try to live together to see if it's fit? To not give it a shit about the "paper" that tight them together? Or, it's just a fashion here?

I am not sure, maybe they have their own reasons to do so, maybe because they have other options.