You'll begin to notice that as you get older, people seem to be more open and "ready" for sexual relationships. Try to explain to her that you're not ready yet to commit to a sexual relationship, if she loves you too then she'll understand. As for her, "needs",
she'll take care of herself, I'm sure that's what she's currently doing so you should be fine it that area.
Try to have a sit down with her and explain what's going on, and you'll commit once you feel ready. As for your previous relationships, it may be because you committed too early, you may not have been fully ready to make a sexual commitment so try to wait it out, for now.
EDIT: Apart from what Soldier said in his first sentence, his makes sense too.
"Of course it isn't going to be the same as before but you have to stop yourself from making it seem so different that you have to leave. It may sound vague but that's what I got."
she'll take care of herself, I'm sure that's what she's currently doing so you should be fine it that area.
Try to have a sit down with her and explain what's going on, and you'll commit once you feel ready. As for your previous relationships, it may be because you committed too early, you may not have been fully ready to make a sexual commitment so try to wait it out, for now.
EDIT: Apart from what Soldier said in his first sentence, his makes sense too.
"Of course it isn't going to be the same as before but you have to stop yourself from making it seem so different that you have to leave. It may sound vague but that's what I got."