I heard that Harry's working on a solo project. (and this will be just plain embarrassing if he isn't, but I don't have an account on any social networking, so work with me here.) This would absolutely break my heart. If he does this, One Direction won't be One Direction. Literally. It takes all five of these boys to be the band they are, and they wouldn't be in the place they're at right now if he didn't audition for the X Factor. The same goes to all of the boys.
Think about Louis, Liam, Niall, and Zayn. They would feel betrayed, and probably like they weren't good enough for him. They would feel like he didn't want to be with them anymore. This isn't gonna change anything, and I totally get that, but I had to say this somewhere.
Apparently right now he's in LA working on the project. This was a stupid decision of his. I don't think the boys and him will be the same again, they probably feel seriously hurt. And I don't know any of them personally, but I do know a human personally. And that's how they'd feel. That's how I'd feel if I were the rest of the boys.
Don't leave, Harry.