Gulluoglu, I'm pretty sure it's possible by vanilla behavior for characters to go and get married without your consent.
If they're desperate for love (or at least, marriage,) they ain't gonna wait around forever for your sorry old arse to play kingmaker as a prelude to playing matchmaker, now, are they? They're not getting any younger, after all. (Well, barring save editing, anyway.)
I have my own, though, and it's very curious. I'm playing as the Duchess of Meath (formerly the Earl of Dublin,) and I fabricated a claim on the other county of Meath before I formed the Duchy. Before that, though, I randomly got a Claim (a legitimate claim? No way!) on one of the counties on the northern coast of Ireland, so I said to heck with it and went ahead and claimed him.
So now I have three counties, and I've been expanding my ambitions: I have my signs on Connacht, and I have successfully fabricated a Strong Claim on it. It's there in my Claims, when I check, in fact.
But it won't let me declare war on the old fart Duke who's all up in Connacht, it's not recognizing I have a claim CB. It recognized other claims - I got his wife and his Martial to join me in a plot to straight frame him for heresy, followed by having His Holiness excommunicate the guy, and I certainly had the Excommunicated Ruler CB valid, and I proceeded to wafflestomp him so hard he threw himself at the Pope's knees and confessed, I guess, because the war ended and I didn't force it to end.
Is this a vanilla bug, a CK2+ bug, or what could it be? It's like there's a disconnect in the game between the bits where it sees I have a claim and it tallies up my valid CBs, but the weird thing is that I WAS able to claim something else on a fabricated claim.