John wasn't totally innocent here (SPOILERS)
I think John did have some sort of attraction to Doris, and not just as a friend.
He may not have been madly in love with her but, for a self-proclaimed shy and boring guy, he certainly knew to flirt with Doris. You don't just kiss someone you barely know (even if it was "supposed" to be on the cheek). The way he acted with her at the concert was not just polite. There was some chemistry going on, definitely. It was even kind of weird that he insisted that Doris come along with him and Brooklyn to the karaoke bar. Most guys on a date would say, "nice to see you" and go off to enjoy the date.
The ending of the movie was left to interpretation but, in all of Doris's other fantasies about John, they were just fantasies that never came to pass. In her last fantasy, it started with "Doris, wait." And as she got into the elevator, he said those exact words. That hadn't happened before. I think it's entirely possible that John may have, at that point, admitted to Doris that he did have some actual feelings for her.