Amhazair:
Maybe in really late game things like that happen, though they are surely not normal.
Of course he can do the backstabbing. Even in early game. Just instead of helping your ally just attacking him. I see that you approve things like that
That game has quite small community. And there are many games that you play. If you do thing like that once you must be aware that it won't be just forgotten. "I will backstab someone today and easily find allies next time I need them" - things don't work that way
You are either ***** [insert what you want here
] that will do absolutely everything to get one more province or you are someone that can be trusted and count in hard times [and vice versa].