I think you might be dealing with the notorious libra-indecisiveness and difficulty with commitment! I don’t know her personally, but if it were ME saying that, I could either be taking it slow so I didn’t make a mistake (a big libra worry), OR I wasn’t interested and didn’t want to hurt the guy’s feelings.
Have you ASKED her directly? Has she ever said anything that makes you think she’s NOT interested in you? If she seems like she really likes you, but won’t take the next step with you, I would think that she’s just afraid of “change”, of making a mistake. You weren’t really clear about what you are asking her for, and what she said, so I can’t tell for sure what I think she means, but I doubt you are just an “ego boost” for her…..that doesn’t sound like something that a libra would ever try to get by using someone. So put that at the bottom of your list of reasons!
And GOOD LUCK!! 🙂