Three childhood friends mimic the devastating dynamics of their parental relationships while in pursuit of love. For one, when love turns to deceit, the family tradition of murder is the only retribution.

Why do your protagonists base their relationships on their parental relationships? Isn't this what everybody on the planet does anyway? So the plot is about a character who murders their cheating spouse? Then what? Why would an audience empathise with this protagonist?

This sounds interesting. I like it.

It might be good to focus on your protagonist however and make it about his relationship. The story itself can obviously be about three friends but if the longline told us a bit more about how love can lead to murder and how it's traditional that might help. I'm guessing his father killed his mother or the like.

It might also be good to mention the setting to help indicate the tone. Is it middle America, big city America (I'm assuming its set in America, it may not be).

Good luck