Ok so my friend Amanda told me not to tell my other friend Olivia that Amandas friend is dating a guy that Olivia likes. Amanda's friend and Olivia are kind of friends and I'm friends with all three of them. I don't know if I should tell Olivia that Amanda's friend is dating the guy she likes or keep it a secret.

It's a no brainer really. You keep it a secret unless you don't value the friendship you have with Amanda.

If you spill this secret you risk losing Amanda's trust.

Why is there a need to break the trust of a friend

True, I guess it's not my place to tell, but it is just hard seeing my friend hurt because she really liked the guy and to have a friend of hers date him isn't right. But yeah It's their problem not mine.