Just to know, i'm not as far in the game to see if it's available or not, is same-sex romance/marriage is available in the game or can it be an eventual possibility for a next update ?

I don't want to enter in debate about it, that's just that can be a good selling point for some friends if i can add this in the game possibilities list.

There aren't any limits on who you can marry. So, same-sex romance/marriage is available. I believe same-sex couples can adopt as well.
I'm not far enough into the game to confirm so I could be wrong about adoption, but this is what I've read on the official forums.

Great! Thanks for the quick response :)