Cheating actually comes in various forms, but all cheating disrupts a stable relationship where each person trusts that the other shall do no wrong or otherwise act hurtfully behind the other person’s back.
Cheating is then typically seen as any secret act where a person does do wrong or does act in such as way so as to undermine the trust in the relationship. From this perspective, cheating can include secret spending, indulging in addictions, and emotional and sexual affairs.
When the secret breach of mistrust has been found out, it is met with upset. To minimize the impact of the event, it is common for people to deny the behaviour or offer excuses to dismiss or minimize the extent or impact of the event. This can create circular behaviour as one person seeks to validate and uncover more while the other seeks to minimize and /or deny to avoid detection or responsibility.
Depending on this cat and mouse game, feelings of mistrust and hurt may intensify, and further harm may be imposed as a result of the lying heaped on top of the actual act of deceit.
For some, any one act of mistrust, depending on the type of misdeed and perceived severity, may trigger a desire to leave. This always remains a personal decision. However, it is important to realize that in the heat, anguish and turmoil of the situation, people may not always use their best judgement.
If you have discovered that your partner has been cheating, it is advised to at least take some psychological (if not physical) space to compose yourself and consider the value of the relationship, the impact of the behaviour, and the consequences of any action before actually deciding on your next move. To this end, counselling is often recommended as a good way to gain perspective, and determine if the behaviour will stop as well as if trust in the relationship can be restored.
Once people have had an opportunity to look at their respective behaviour and responsibilities, whatever that may be, then they are in a better position to determine if they should stay or go, and figure out what necessary steps must be taken to minimize further turmoil if they decide to stay.