I'm going to preface this with I don't know you and I honestly do not mean to offend but the only way I can think to reply to this is by offering some rhetoric questions to think about, if that's ok.

You use the words line and 'scared of crossing' - so the obvious question here is what are you scared of? If you can quantify that fear, you may open some doors that will help guide you to an answer.

Here's where it gets sensitive and by no means answer this here, ok?
What's your self-worth like? Do you see yourself as deserving of someone else's time - if only for a night? Are you afraid of being vulnerable to someone else? Are you afraid of showing your body to someone else? Are you afraid of not knowing what you're doing - of coming off as inexperienced?

There's dozens of reasons why you might freeze and retreat, but I hope this gave you some things to think about.