Physical signs to look for to identify whether or not someone is having an affair are lipstick on the collar, odors of cologne/perfume on a shirt/blouse, ensuring underwear for secretion stains. how to catch a cheating spouse? You can also check their wallets and/or the glove compartments of their car to see if they left receipts, pieces of paper with phone numbers, addresses, condoms, etc. You may want to check your spouse for two weeks.
During this time keep track of the mileage on their car. Monitor the time they leave for work and the time they come home. Keep a calendar and note the times, this should help you establish a pattern. If your mate claims to be working late, check paycheck stubs to verify this overtime.