I like my best friend's crush...

        I like my best friend's crush. She's liked him for years and kinda called "dibs," as stupid as that sounds. I'm pretty confident and I persue the people I like, but she's really shy and will likely have a crush on him for years to come and not do anything about it. I also feel like we would be compatible, whereas they might not (yes, I know I'm biased). 
        But obviously I don't want to be a bad friend, so I can't do anything about it. When I have a crush, I usually keep it for a long time. How do I stop liking someone?