Why does my sister need to steal all my boyfriends?!?

So my sister is 17 and every guy thinks shes hott she's popular she's captian of the girls varsity soccer team and has all the coolest clothes because she needs everything she wears brand new. Im 15 and am an athlete too on the volleyball team and every boyfriend i have always wander off and go look for my sister and then a week later he brakes up with me because they say my sisters prettier, WHAT DO I DO??!??