Though having sex or kissing someone who is not your partner is a form of cheating, there is another forms of cheating that should not be permitted. It is debatable that it is technically not cheating because nothing is being physically done, but there is a counter-debate that states otherwise.
The first form of cheating that everyone is aware of is when someone goes outside of their relationship and performs a physical act with someone else, such as having sex, kissing, or holding hands. Granted, it may depend upon the context of the hand holding, but when it all boils down no one holds hands because they are simply friends.
It is very common for a relationship to end because someone was being unfaithful in their relationship. However, the other form of cheating is emotional cheating where someone invests themselves emotionally into someone outside of their relationship.
In this case, a person may begin a relationship with someone that is based off of emotional intimacy, which can result in emotional and or mental distance with their partner. With emotional cheating, a person becomes wrapped up in how someone who is not their partner may treat them; one reason is their partner may be lacking in doing so.
You no longer cater to or care for your partner’s emotions because you are so emotionally involved with someone else. Eventually it will cause a huge wedge in your relationship and end up in a failed relationship.