I've pretty recently purchased the game (on 1.5.8 I think) so I didn't really experience how bad the snowballing was early on and looking at the related topic, at least one dev really worked hard to fix it but the solution is definitely cruel to player. On my playthrough we, Aserai, never declared war to anybody actually since I joined as a vassal. They granted me the recently conquered Danustica, we made peace after a while and this lasted for some time. This was the only peace we had since I joined them. Until I eventually snapped and killed half of nobility, the cycle was something like:
- we gain territory from SE
- Khuzaits declare war
- we lose the territory to them
- make peace with SE
- gain lost territory back from Khuzaits
- SE declares war
- we lose the territory to SE
- make peace with Khuzaits
- gain territory from SE
Whenever you feel like making some progress on one of them, the other declares war on you. Well, I'll be honest. there has been numerous times SE and Khuzait fought against each other as well... for ONE DAY and immediately made peace. This becomes so tiresome eventually, you can't focus on any other aspect of the game from waging war. I've been away from home for so long fighting wars that my wife, who was a governor back in Danustica, calls me "friend" now when I talk to her. No hope for a dynasty anymore I reckon.