Wait. I don't know the post this responds to but it seems like the more I win the more the opponents war weariness (mine seems to stay minimal ... maybe my civics and wonders?) ... so it appears that winning or losing does matter, yes?
War weariness works like this:
If you attack, you will get 1 or 3 WW. 1 if you win, 3 if you lose. Not sure where withdrawals fall. No WW is suffered for attacking in your own culture. Note that this is CULTURE, not borders, so if you lose a city, the borders may change, but the tiles will still be yours for WW purposes (the city tile will show their borders, but the % culture of the city should be more than 50% yours, and so it is considered YOUR tile for WW, even though it isn't in your borders)
If you are defending, you will get 2 WW regardless of outcome. Again, no WW in your own culture.
The culture thing is really important if your war stalls after you take a couple of cities from an opponent. If you keep defending the cities you just captured, you will keep suffering WW and your opponent won't, because he's fighting on his tiles! Incidentally, this is a big reason why the Statue of Zeus sucks so much; if your attack is going well, all the fighting will be in the opponent's territory
and they will not be suffering ANY WW
To quote another poster named Beamup:
"An observation: This means that you'll be much better off, in terms of WW, to let your enemy's stacks come to you and crush them in your own territory before you start your offensive. The less of their mobile forces you have to destroy in their territory, the better.
Which means that your people will actually be happier if you let the enemy invade and trample all over them instead of keeping them safely away from your cities. Go figure."
Of course, tacitcally, you shouldn't be declaring war if you aren't invading that turn (unless maybe you have both the SoZ AND the GW -- to make his people angry and give you more GG's -- and his army was already on your borders and you can take it out with ease in a turn or two after it moves into your territory), as the longer the war is, the more troops he can build, obviously