I need to specify that I don't own the GoG version (bought it on Steam).
But you never know, maybe someone can help here.

Basically I've been playing EU:Rome for a good week and never crashed a single time, but now it's crashing so much you would not believe it! Maybe is a late game problem? The crash only happens when I try to see characters details or when I want to change a governor/general. So annoying.

Howdy.
Os? Graphics card?

That'll help!

Windows 10; I'm using an integrated graphic card and not my Nvidia one (because personally I don't see a lot of difference and I can save some power in this way. Could it be that maybe?). By the way I've started a new game some days ago and have had only few random crashes for now. Perhaps is a end game problem.

Hmm so you're playing on a lappy connected to a display, I suppose.
Probably it, man. Had tons of issues running these through intel hd cards until I started using radeon and nvidia cards (2 laptops to be fair). Windows 10 and 7.
Well, there's some info on the web available but I say: you're better off with dedicated gpus.
Ciao and good luck!

Alright, I will be playing with a dedicated card then. Hope it'll fix the problem!

Lemme tell ya personally: the best experience I've had with -older- paradox titles was on an old franken-potato I built with spare parts. Win 7 + some 512 radeon card, 8gb, i5 and so on. Played 100+ hours of For the Glory and EU: Rome in it (plus some oldies I was a bit tired to fiddle with regarding windows 10, such as Jedi Knight and so on).
But then it literally exploded and I got this crappy lappy. Yep.

c ya! and post results 'ere!