If you're insecure about your relationship and worried if your S.O. cheats on you, then this bed might just be for you. It's called a Smarttress - a mattress that can detect when the bed has been used for other things than sleeping.

Check it out:

It will measure the duration and intensity of movement on the bed and send an alert to your phone when it hits the danger zone of "impact per minute." Meaning..you have some evidence there!

There's also a demonstration:

That said, if you can't trust someone to be faithful in a relationship, you shouldn't be in one in the first place.