@Nep @mekrabbat That's assuming that he wouldn't benefit from her remaining alive indefinitely, and believing that as a woman, once she submits to him/loses her virginity and her power, she'd be unable to escape from his clutches [as was so often the case for women during various parts of recorded human history], thereby assuring him his power and prestige. That's likewise assuming that he didn't covet her as a trophy/object of romantic affections/lust.
Likewise, he's falsely assuming that she'll tell the truth and convince everyone that she wasn't kidnapped and asked for an out from him/asked for aid to get attention from Dion. Once she gets into the hands of her allies, with him in custody/surrounded, she can change her story to the truth. What's he going to do? "He threatened my life and I went along with his scheme until I was safe in the ranks of my family's forces/my allies, and then made sure the truth comes out such that he or his house might never repeat this."
Unfortunately, revealing that she was kidnapped by one of the Ducal houses' lords will weaken the Ducal Trio's power by at least, 1/3rd (stripping them of lands, wealth, and power) and likely further stress the interest that Dion (and his brother) has(have) in her. She'll have an even
more difficult time getting the marriage annulled. The noble made a major blunder due to his unrepentent and unrestrained greed. The future looks to have numerous possibilities.