how do you guys deal with jealousy/envy any advice for my case

i know this is a general question but i have been finding myself extremely jealous of my cousin, like she is around my age but she gets a lot of attention from guys and she also has had a loving boyfriend since many years but i have never been in any relationship and i think i will be single forever, she also has a big group of friends while i have only two despite trying and she is so much smarter and more popular than me, mostly i am jealous of her having a good boyfriend who is actually such a pookie bear typa guy he genuinely is a green flag and wants to marry her, why is life unfair i wish my life was as good as hers.