I think the grandmother lied and he did want to go home. But you’re right the situation rushed too much and there wasn’t any realistic development of feelings.
That was a mistranslation. Hatoyama never said that. He actually said, "That is not what I mean." Nowhere in the raw Hatoyama ever mentioned of having no interest in dating Hitsuji.
I forgot to add that in my comment (it seemed out of place so I was wondering), thanks for letting me know! Still a lot of missing/skipped parts to the story but this changes things
didn't he say he didn't want to go out with him in the beginning of the chapter? kind of ruins any later feels since they didn't talk about it and at the end he's just like hey i'm in love with you - too rushed, didn't see the development.. hard to believe him.. oh well