Here Is the Beehive by Sarah Crossan

Ana and Connor have been having an affair for three years. In hotel rooms and coffee shops, swiftly deleted texts and briefly snatched weekends, they have built a world with none but the two of them in it. But then the unimaginable happens, and Ana finds herself alone, trapped inside her secret.

How can we lose someone the world never knew was ours? How do we grieve for something no one else can ever find out? In her desperate bid for answers, Ana seeks out the shadowy figure who has always stood just beyond her reach – Connor’s wife Rebecca.