What happened?

So I was playing as France and I had several Nations friendly,Very friendly, and indifferent. I liberated Romania invaded and declared war on it several times because to get anything I wanted from the British by offering to declare war against Romania. Turns later every nation nation is Hostile and the only nation that is indifferent is Westphalia which I just liberated. How do I get them to like me?

Go to your diplomacy panel and see.

Mouse over the various factions on the panel and see what is effecting their dislike.

It is likely an expansion penalty which will slowly reduce, or it could be something else.

It should be the same for most all of them.

If it is that important to you, you will need to give them gifts, money, and technology. Alliances and trade agreements help.

That is if it matters. You can always ignore it and just win the game.

Well, for starters I would stop trampling all over Romania!

What's probably happened is because you were making Romania a protectorate, and then turning around and stabbing them in the back by declaring war on them and repeating, the rest of Europe likely now has quite a large diplomatic penalty against you. Doing things like breaking protectorates or not going to war on behalf of an ally cause a penalty each time that can take many turns to get rid of.

At this point, you've probably got everyone so irritated that it'll either take too long or cost too much to reverse the penalty, so you may as well just go on a conquer spree.

I would say if you want to go back and conquer liberated territories, the best idea is to burn and loot the capitol and let the territory rebel rather than liberating it and making it your protectorate. Attacking a protectorate is very bad for diplomacy.

Yeah now I can take advantage out of this. Like I was sieging Hannover and the Batavians come and take the capitol themselves. And theres a nation in the middle of France the Swiss. 2 members of the Coalition down to remaining... WWI!!!!