I read a fanfic on fanfiction.net not long back called Playing House. It's about when they're older and still friends and Ron says to Hermione:"If I kissed you…You wouldn’t ask me why? You wouldn’t stop me?”
I suppose it explains his behaviour even if Jo didn't write this herself. He was scared she would go off on one. I suppose Hermione needs to encourage him a little more. I really hope they get together!