I'm quite upset at your love interest tbh. It appears she has the avoidant attachment love style. Avoiders usually want the love but not too close, not officially enough as to make them responsible for another person's happiness, and not so demanding as to make them accountable. They want to be able to breeze in and breeze out, not because they're unfaithful, but they'd rather not confront the hard work it takes to make things work, and surface level interactions, affection amd attractions often fill their love tank enough. It's a conditioning that resulted either from her background or her past romantic relationships. You'll either tire one day and the emotions will settle, or someone else will come into your life who returns your love so madly. I truly hope this girl gets sense early. Perhaps, brace the fear and ask her to define this because you absolutely are tired of the uncertainty. You too deserve to be be loved. Let her stop using you.