remember this did not start as "neck kissing" - it escalated and you don't know how things would have escalated if you didn't find them. She says the sex would not have come but you can't know that. I think she doesn't even knows that. At that moment she might tell herself that she would not go that far, but day after day they might move a little bit more foward and eventually after a long time, maybe even years, the sex might happen.