What does this mean?

What does it mean when your crush is your best friends' enemy and they never once got along because they were mean to each other but it was your crush who started it first. And whenever your best friend is around you and your crush, your crush is nice to her all of a sudden but when your not by any of them your crush and best friend are enemies again. My best friend has told me a bunch of times that they are enemies but when she's by me and my crush is near me and we start talking to each other he's nice to her but then when they are by each other and I'm not by them my crush is mean to her again. What does it mean when your crush and your best friend are enemies when your not by them but like friends when your by them????