Check bank statements and cleaning habits, suggests marital sleuth Lindy Grant
"Your partner starts losing weight, doesn't want to go on holiday, needs to buy cigarettes or walk the dog at strange times of the day or night. When you try redial, it's always the speaking clock - they've dialled another number after speaking to their lover. Their briefcase is locked in the car, or the combination's changed. Their clothes change. Bank statements show they are withdrawing a lot more cash, and in places you wouldn't expect them to be. People are careful about putting things like restaurant bills on their credit cards, so they get out cash and pay that way. One woman found out her husband was seeing a prostitute because he was getting a certain amount of cash out every single week, at a time when he was disappearing for only 45 minutes. Men will make sure there's no smell of perfume on them, no lipstick or blonde hairs; but they are not aware that women notice when they come home showered. One man came home with his underpants inside out, another with a sticky label on his back saying "I've already had him today" - those are dead give-aways! Men who are having affairs either become very attentive and you start getting flowers, or they switch themselves off from the family. Women are better at having affairs than men - unless they've fallen in love, and then they normally leave. Most husbands come to us because they've noticed their wife's attitude to sex has changed - either there's something different in their physical relationship that wasn't there before or she's gone off sex"

Lindy Grant runs S & Elle Investigation and can be contacted on 01428 609009