Holy crap, I just had 35 dreadful years as the lesser partner in a union with Georgia where I could do nothing. Agh. Euh. Blarg.
Yes, lower relations below 0 and you'll get out when the monarch dies. After all the "ignore"-events, I should've been somewhere around -500. As if it helps if the bastard lives forever. He had awful stats at that and I didn't even have any BB to shave off.
No, what I want is some mechanic to break the union at will. I'm not asking for it to be easy - hit me with -6 stab and rebels or anything - I just want the possibility. Please. In the meanwhile, I'll hiss and and scratch up my furniture every time I get a royal marriage proposal.