Girls, why is she so reserved with me even though she's really outgoing and friendly to others?

So basically there's this girl whose beautiful and all and one of the really outgoing girls of my class. She's nice, talkative and friendly to everyone but me.
I liked her a lot and just went to approach her a few times but she never makes eye contact when I've tried to talk to her and she likes looks at her phone or she remembers something and leaves midway the conversation.
I tried texting her and she usually replies to every text but she's never initiated a conversation herself. She also kind of just replies to my texts and never you know kind of ask me about anything.
I'm a bit of a serious looking guy (that might do with most of it) but am generally an attractive guy (I've been told). I don't really talk too much least to girls but am a kind of popular guy in my class having a few crushes on me. So if I usually talk to any other girl they aren't hesitant in talking to me and we usually ho nice. So I don't have an issue with girls usually
but Why is she like this? And that to just around me... Do I give off being creepy?
Girls, why is she so reserved with me even though she's really outgoing and friendly to others?
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