War weariness: can someone explain?

[Dry]

Here is the background:
Huge world, 16 countires.
Somewhere around 1200AD, Babylon declared war to Germany. Babylon was then helped by 2 other nations against the poor Bismarck "Du arme Schwein".
Followed then a very confusing geopolitical situation with countries declaring war to an other one, but not to his allies making it possible for one to ally with the ally of his ennemy.

Anyway, in this game, I (Mam'zelle Angele of France) decided to enter the fighting arena and declared war to the US.
As soon as I attacked his first city, his allied civs (England and Persia) declared war on me.
By the time I conquer all US cities on my continent, Egypt joined me against US and China joined the US-GB-Persian alliance.
So, to summarized, I declared war to US only, but was at war against 4 countries.
As soon as the last US city on my continent felt, we made peace. While still at war with 3 other countries, people of France stop complaining and even starts 'Loving the Mam'zelle'. I first thought this was because I did not attack/put one foot on the ground of any other country than the US, but later, I attacked China and ... no complains at all, except from conquered chinese cities complaining I was attacking their mother country.
I am now still at war with GB, attacking his cities and no complains of anybody (Chinese citizens are happy: I made peace with what is left of mother China).

Does someone know if the war weariness has something to do with whom declare war to whom?

[WarKing]

Here's the short of it all:
If you declare war/if you are the aggressor, then your people will complain.

If you are attacked/if you are the defender, then your people will want to fight.

So what happened in your situation:
You attacked the US, you became the aggressor, then the alliance attacked you, you became the defender, this probably balanced out everything. In fact, I think your people may still love you for defending the nation.

Personally, I have never had a significant problem with War Weariness, if anything I've only noticed their love for their defender!

Be the hero, not the tyrant.

[Moraelin]

Actually, it's just that war-weariness is only one of the many factors that keep your people happy or unhappy.

If you have lots of luxuries and cathedrals, your people may throw parties even when you're the aggressor. On the other hand if your people were just below the limit of revolting before the war, then even being in defense will throw them into open rebellion. (Yes, I've had a long war where I, as Greece, was attacked by the Romans. And the half of the Greek cities went rebelious because of war weariness.)

Also, during the course of a war, certain things can change. E.g., if during your conquest of the Americans you've secured a source of luxuries that you didn't have before, it can tip the scale quite nicely. It can also be that the governors converted some people to entertainers in the process. But the opposite can happen, too. If during a war you lose a source of luxuries, it can make everything go downhill. It doesn't even mean losing a citiy. If I'm importing furs from Russia and we end up in a war, the trade immediately is broken, and my people may become unhappy for lack of luxuries.

And finally, as you know, there are certain buildings which can severely reduce war weariness.