That's sort of complicated . . . First, Vincent did not appreciate that Yuri was taking up abuse to do something for Vincent from the beginning of the date. He isn't the kind of guy who wants things from people, so he didn't like that Yuri went to that extent. The proper reaction would have been to punch her in the face, especially when Vincent was strongly associating Mother to how noble culture would naturally treat Yuri. You know, those fuckers.

Then, Vincent put together that Mother had hurt Gilbert already then she was hurting Yuri, so it was natural to make that possessive shift when you already have Gilbert already primed in Vincent's mind. It also caught back to that same frame of thought where he doesn't to be given something that actually has a cost. On top of that, Vincent also could tell he was hurt less than Yuri, and he had a pretty super idea why which was only more infuriating. Reflecting on it that way, Vincent may blame himself for the incident while logically understanding that Yuri did all of this on his own without being asked or told which is why that question came up . . .

When will Yuri be drinking his feelings into oblivion? If that is, you know, a thing that will happen. Also, Yuri's thoughts on Vincent trying to finish him off with his own hands? I will stop asking date questions soon . . .