It's not okay to do things that hurt a friendship.
Jenny is in love with her best friend Sue's ex-boyfriend.
She wants to be in a relationship with him.
Jenny asks Sue to talk and tells her she would like to date Sue's ex.
Jenny sneaks behind Sue's back and starts secretly dating her ex.
Sue gives her blessing and thinks they will be happy together.
When Sue finds out she is hurt and pushes Jenny out of her life.