⚠️There are Spoilers.⚠️
In my opinion, he loves the MC because she was kind to him, so much so that, in the route where the MC doesn't help him, she simply dies because she didn't get his attention.
Not to mention that when the MC asked if he didn't confuse her with someone else, he said no and that he simply liked her, but it could also be that the protagonist resembles Columbina.