defensive pact

I've declared a war against Ottoman that had a defensive pact with Zulu, so I were warring both of them. However, after some time I made peace with Zulu and focused only on Ottomans, despite the fact that they still had a defensive pact. It's pretty weird to me, but maybe it's indented? Discuss.

There are two major problems with defensive pact right now, first pretty annoying and second is kinda severe one. 1. You are in d. pact with some civilization, and your ally declare war on the third party, who have some vassals states, happens really bad thing. Game mechanics works in the way...