Again this can be attributed to their guilty conscious. They tend to begin losing interest in activities at home. Ignoring family events, children, and even routine chores, can be a sign that something is going on. Often there is a general change in their attitude toward the entire family. Grooming habits will change.
Clothing can often show signs of an affair.
This applies to affairs from a financial point. Keep a close eye on money, check and credit card statements to see if they are spending more than usual or in places they are not normally involved with. Keep track of the mileage on their vehicles and compare it with the distance to and from work. If a person should be driving a daily total of 25 miles and there are an unexplained 50 extra miles three days a week, it may be a direct indication of concern. This is becoming a greater possibility with the advancement of technology and the ease by which sophisticated equipment can be obtained or even made.