It's wrong to have a crush on your friend's partner.
Justin has noticed that his friend Nick's new girlfriend is very kind and pretty.
Justin wants to get to know Nick's girlfriend better.
Justin knows that he can't act on his feelings, and decides to just treat Nick's girlfriend as one of the guys.
Justin goes behind Nick's back and tries to kiss Nick's girlfriend.
They all become best friends and Nick and Justin's friendship is stronger than ever.
Nick's girlfriend tells him about Justin's behavior, and both decide never to speak to him again.