Why do people make fuss and are jealous of others in a relationship

This happened to me recently in school as I was close friends with a girl and she liked me more as a friend and we were getting along and she was one of the pretty girl if you know but she was different as she never had a relationship and she never smoked or vaped before and neither did I and out of every guy in school who asked her rejected them, and as we are besties but in a relationship alot of people started to get jealous of me including the girls as they wanted her as she was popular because of her looks, and one day my friend decided to use my phone for some reason I thought he needed to search something because his phone was dead of charge and basically unknowingly he took pictures of the message from his phone that he lied that it was dead and leaked it to the whole school and majority of the guys and girls that got rejected or liked her are against me as they wanted me gone because I just won someone who has the same liking and common as me, and they keep saying that “she was a bad person, she can set you up” and I don’t believe that because I know how she is, she told me all of her feelings and life and herself and she is honest and loyal but maybe they’re making some rumors and telling me to block her because I called her beautiful and saying I’m a simp even though she treats me better and make me feel pretty than any other girl does and what are they’re trying to do take away someone I loved, idk if I should take action or leave it because majority of the people in this school are insecure and clowns as they never have any attention from a female unlike me and they’re just taking this as a big problem instead they could go to some other guy and do the same thing? Why me!?