Why my crush's friends laugh at me when I am around?

Actually i am a 21 year old student and i like a girl so much from my second year and this is my final year. So at first the information of liking her was already out to my friends. Then the situation got so complicated that my feelings were more like one-sided and i got so attached that i don't even try other girls and i am waiting for her only. At first she was looking at me and smiling but then she kind of was not interested in me , it was may be because she got so popular for her beauty and a lot of boys proposed her. But my feelings remain unchanged and it only grew. I messaged her and she blocked me, between these two years my friends started to hate me (i don't know why), She became my crush and this feelings is growing stronger only. I am kind of good in academics so i anonymously help her doing all projects ppt etc. She indirectly knows that i am helping her but she don't talk to me and her friends laugh when i am around (like if i am in alift with her and her friends then they smile and it beats the shit out of me. i feel like i am getting insulted with my feelings. i can't also even reply them because i don't have the nerve.) What should i do i don't even know if she like me or not. kindly give suggestions.
Why my crush's friends laugh at me when I am around?
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