Bob Mom actually walked out pretty much as soon as she was born.
Sorry to hear that. Proper age if you want to put a point on it would be 18, but some girls here have it less and it gets murky. You're her dad and her mom and that's never easy.
What can you do? You can talk to her about boys, and you can make it real clear to her that a boy who would to do that with her is not someone that she should respect....which I also get is a tricky conversation since you did that, but it's the reality of the situation.
As a parent I suppose you can also say to her that it isn't something you want her doing within house rules - but honestly, the biggest problem here is clear. You have to talk about boys and her sexuality, which she's only discovering. And I do mean talk - discuss - not you telling her what to do or reacting with menace or she'll shut you out.
