A secondary participant end whole war

[IIWW]

Situation: France, my ally, lost a war some time ago, and were forced to release Guyenne (I wasn't able to help, they lost to GB due to occupation of wargoal + some overseas provinces. Nothing to do). Then I DoWed said country. France besieges every province, doesn't transfer occupation (no surprise) and they demand that Guyenne becomes MY vassal, thus ending the war (G. had no allies). I'm not sure if thats WaD, it sure is weird. Oh, and I got "separate peace" modifier. WTF?

 

[Thrake]

Let me guess: then, France turns hostile because of "wants our province", breaks alliance and DOWs you?

 

[IIWW]

Let me guess: then, France turns hostile because of "wants our province", breaks alliance and DOWs you?

Weird enough, no. They loose cores when they release a nation, so maybe thats the reason. They want these provinces, but it's like -30 modifier (for this and parts of Milan). Maybe strengh of country has something to do with it, I revoked privilegia whith f.e. Austia having everything up to Constantinople.