What's the most disturbing secret you know about someone that would ruin their life if exposed—but you stay silent, pretending you don’t know?

My friend’s sister has the perfect boyfriend—sweet, loyal, totally in love with her. Their families are already talking about weddings, and everyone thinks they’re meant to be.

But my friend told me the truth—she cheated. More than once. And yet, she keeps playing the perfect girlfriend while sneaking around behind his back.

I see them together, all smiles and future plans, knowing it’s all a lie. And I’m the only one who knows.