Things just progress how? please repeat boss
Mate you're from Poland so you already know. But anyway, as you know it's usually something a bit like this:
1. You live your life, like you do your hobbies, go to work/school, you basically just go out and be around people.
2. People of opposite sex that you're interacting with might take an interest in you. You notice their tone, body language etc and decide if you wanna date them. If you do, you respond in the same manner and you start going out. You might also subtly show your interest this way first too.
3. If both parties are happy how dating is going, they usually have a rather explicit talk on "making it exclusive". But it's also very often that it's a very implicit shift from dating to being in a relationship.
4. Might marry your bf/gf down the road.
Long story short, dating/relationships/marriage is a natural extension/activity of life like playing basketball or going to the movies in the west whereas it is more of a business in the east.
An interesting point is what happens in number 2. You'll see that number 2 allows for sheer (natural) selection which is exactly why westerners arguably have superior physical attributes (on average) than easterners. Sorry if I hurt any feelings but that's biology.
Does that marriage naturally progress to a divorce as well?
Yeah usually the people decide on getting a divorce themselves whereas it's usually their parents/relatives in eastern countries. Eastern culture = "tribe", Western culture = "individual". That's why.