Harry was inept. But he wasn't COMPLETELY daft. He saw the way she leaned in, and that she was smiling, and he grinned back a little, starting to lean back in.
He'd only just started to kiss her when the part of his brain that Harry would probably term "sensible" and Ginny might have another name for kicked in. "Ermm," he leaned back again, taking a step away.
Harry was hunting down bits of an evil wizard's soul. People were trying to kill him every other day. It wasn't fair to Ginny to get her any MORE involved in that, and Harry couldn't let himself think about how nice she smelled, or how soft her lips had been. He had to be practical because he couldn't HAVE a girlfriend.
Not to mention the best-friend-shaped redhead who would punch him in the face when he heard. Though that was, admittedly, an obstacle Harry probably would have ignored, normally. "Ginny. . . I like you and all. But I can't. . . we shouldn't." Bugger. "I mean with everything going on, we should just. . . be friendly. Not. . . snogging friendly." Harry wondered why she even WANTED to snog him, considering he was such a prat around her most of the time lately.