Responses
I see the speech bubble and acknowledge that it can easily be interpreted that way, but wasn't he just answering Ume as he was struggling with her name? Maybe Ume has to continue fighting for him though... it sounded like he was saying "yes, thats my current girlfriend, but you're getting her name wrong". Like hes answering that that is his girlfriend rather than that she's who he wants to marry. It showed that a running gag between them is that Ume doesn't know his girlfriends' names.

Hopefully he meant that he wants to marry Ume, i dont remember him specifying a person, Ume just kinda started going off about his girlfriend. What Ume should've done is make him jealous.