Agree with the posts above. Love is not rational, so choosing someone who is "better" for you... it just doesn't work that way. If we chose our partners with our minds and not with our hearts, romance would be dead
And besides, while we're on the topic, everyone's talking about how Mashiro needs Sorata to... well... survive the day, but I think she's evolved a lot from the start of the series and she's pretty much capable to (sort of) take care of herself. I'm sure she'd be able to blow dry her hair, but Sorata's been spending a lot of time with Nanamin, and Mashiro realised that she can spend some time with Sorata like this (at least that's how I see it, I may be wrong
). And it's not like he minds it (if anything, he seems to be enjoying himself a little). I don't think it troubles him anymore. Maybe it did at first, but now I think he has less work, perhaps?
And, even though I got a little distracted, my point was that Sorata needs Mashiro too. Let's not forget, the man ran to the airport
begging her not to leave him.