And it's pretty expensive...
It used to be a smudge of lipstick on a collar or the crumpled bill of a fancy hotel discovered in a pocket.
These days it's more likely to be a trail of texts or a secret 'cheat' phone (discovered Dr Foster-style in a hidden compartment of a car).
But now there's a new way to discover whether your partner is cheating on you: and it's a mattress.
What is dubbed the 'smartress' is designed by Spanish company Durmet and will set you back a considerable £1200. In return for the high price tag the makers of the mattress claim it will track what is dubbed 'suspicious activity' using 24 specially placed pressure sensors. These will notify the owner via an app on their phone if their partner is in bed with someone else. This is - rather awfully - called a Lover Detection System.
The technology is pretty advanced, creating a 3D map of the bed which shows in real time (gah!) which areas are being used and how much pressure is being applied (presumably so you don't mistake your dog slipping upstairs and jumping on the mattress during the day for a cheating partner.)
The smartress is of course designed to be bought with the 'utmost confidentiality', presumably by someone prone to suspicion, or who has been burned before and wants to make sure the person they're with is trustworthy.
http://giphy.com/gifs/YvJJbFPBaUKUU
Even so there's obviously a rather large hole in the plan. When most partners cheat it's outside the home, since it takes a whole other level of brazenness to commit adultery in the bed you share with your husband or wife.
Still, each to their own...
