Well I hope you love your cousin in a family love way since that would be the real life definition of the song sweet home Alabama. But I’m guessing you’re probably very young? Well, if your crush is in a relationship then you probably can’t love them. And your cousin is your family member which means you should NOT fall in love with them for the safety of your family. It can cause some creepy problems in the future. Try ignoring both of them to lose attraction. I hope it works out!