Cheating is the worst form of destruction to your relationship or marriage; it is already considered a betrayal of the vows they took when they got married. The discovery of the act of cheating by the other half can either break the
marriage or make it stronger depending on the strength of their love for one another.
Cheating generally means that you are not fully satisfied with your current partner or you feel that something is missing in the relationship. If you were completely in love and happy within your relationship, why it might happen that your partner have an affair? Trust is a big reason, not of your partner, but yourself. Probably for some time you have sensed something is different or questioned the change of behavior in your partner. Nobody deserves to be cheated on, no matter what state your marriage is in and if you believe your partner is having an affair now is the time to check it out and do a little investigation just to be sure.
Start by looking for the obvious things such as a change in the way your partner dresses, a sudden desire to look good, a change in work patterns, an unusual interest in the gym, secrecy over phone calls or emails, a loss of intimacy in your marriage, lack of sexual interest or distance between you that never used to exist. In the worst case you may spy her.