Common signs or clues that your partner is cheating include a major and sudden change in general attitude and attire, a lower level of intimacy and secrets that may begin to become obvious. In addition, a sudden need for excessive privacy and secretive phone calls can be indications of a cheating partner, according to About.com.
Major and sudden changes that could indicate a cheating spouse include sudden changes in appearance, such as wanting to suddenly look more impressive. There may be more frequent trips to the gym or salon. A good indication that this is a sign of possible cheating is if the person was unconcerned with these things before.
When a person is cheating, they are less likely to want much intimacy with their current partner, as their time is being divided. In addition, lies start to become excessive and discovered. The cheating partner will likely become quieter and less interested in family and family activities.
Finally, a clue or hint that your partner may be cheating is if they develop a sudden need for excessive privacy. A cheating partner is likely to walk out of the room to take phone calls and spend more time on the computer and other electronics to surf social networks.