Here's the first tip in tracking infidelity: If your partner is keeping a distance from you or avoiding family and friends, there are chances that he or she is cheating on you.
Here are more ways to find out whether your partner is seeing someone else while still being in a relationship with you, reports femalefirst.co.uk.
Distance: If he or she is not making an effort to be affectionate with you anymore and tries to avoid your advances, then it is possible that he/she is getting emotional satisfaction elsewhere.
Avoiding family and friends: Observe their relationships with your closed ones. If they have changed, it's a signal that he or she is cheating on you. Has your partner stopped doing what he or she used to earlier like taking your mother out to catch a film each week? Did they used to like catching up with you and mutual friends, but now hate the idea?
Mobile phone junkie: Often see them phone texting? They might be sending messages to their other lover.
Private phone calls: Another hint of infidelity is when they leave the room to take a call.
Enough of the nagging: Constantly looking for fault in you justifies why they are having an affair. The fact that the two can hardly stand each other gives them an excuse to look for someone else.