Well, surprisingly, DarthEnderX is right, though.
Ah, so thatīs why I donīhave a gf (and because Iīm fat ...). But seriously, I think there should be a difference between friendzoning and what happened here. A typical friendzone, to me, starts with only one goal in the guyīs mind: "I want to get her, but Iīm not sure how." Now, from what we saw so far, Sinonīs friend isnīt like that. He cared about her for an extended time, always being there for her, knowing about her dilemma and all. ALSO, judging from her reaction, she knows about her friendīs desires. She wasnīt acting as if this was the first time he approached her romantically, saying "Iīm not ready yet" with a little blush on her cheeks.
Mostly, though, I hate another girl falling for Kirito. Shitīs annoying. Being friendīs with Kirito means that, as a guy, youīre out of pussy forever, lol. Wonder if Klein has any chances at one of the girls that is not Asuna. I guess not :/