The Strangers We Know by Pip Drysdale

Imagine seeing your loving husband pop up on your best friend's dating app. Now imagine that's the best thing that happens to you all week...
When Charlie sees a man who is the spitting image of her husband, Oliver, on a dating app, her heart stops. Her first desperate instinct is to tell herself she must be mistaken-after all, she only caught a glimpse from a distance as her friends laughingly swiped through the men on offer. But no matter how much she tries to push her fears aside, she can't let it go. Because she took that photo. On their honeymoon.

When other signs of betrayal begin to surface, Charlie does the only thing she can think of to defend herself-she signs up for the app to catch Oliver in the act.

But Charlie soon discovers that infidelity is the least of her problems. Nothing is as it seems, and nobody is who she thinks they are...