Why is she laughing at me?

It is pretty bad guys, I normall never do this but Im very into a coworker. Anyways, I've had a few awkward moments around her afterwards she always laughs and it really sucks. It can be something as simple as offering to help her and she'll giggle a second about it. Should I just stay away from her? Isn't it a little rude what she's doing?
Why is she laughing at me?
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