Goodreads asked Simon Kettlewell:

Where did you get the idea for your most recent book?

Simon Kettlewell 'The Truth About Us' is actually based on real people- a husband and wife in a long marriage where the husband begins an affair with a younger woman. Believing it won't last, the wife invites the lover to come and live with them. I won't spoil the story. I got the idea from a documentary I saw a few years ago about different types of relationships and how people manage them. Fascinating stuff.

flag