He did not strike me as a "good guy" but more of a beta male. The fact that he jumped on the "I love you" train as soon as Sinon started talking about another guy just screamed insecurity...which is not attractive. That and I am not sure what else you expected, the fact that he has always been there for her probably means she considers him a friend. Friend zoning is real (and natural), and as a guy if you don't know what kind of conduct gets you friend zoned, then more than likely your not the type that "gets the girl". As Kraco mentioned, he gave her the wrong kind of attention over too long a period and now she doesn't think of him in a romantic way.
I agree that scene with the nurse was overly pathetic. Kirito has been killing people and seeing people die with 0 fucks given until this episode.