Being in a committed relationship takes a great deal of trust for the people involved. Each partner must avoid the temptation to break the rules of the relationship, and they must trust their partner will do the same. When a person decides to have another relationship without leaving their current commitment, they are hurting their partner. There is no excuse for their reasoning because it is often simply a matter of convenience or excitement. They tell themselves the other person will never find out, and it will be okay because this is only a temporary condition.
People who cheat on their partners always have justifications. These reasons are generally excuses to blame anything but their bad behavior when their partner catches them and explanations are demanded. They cite such poor excuses such as being misunderstood or unhappy, and their partner might point out none of this was ever mentioned to them. Some cheaters will even blame their partner for their justifiable anger. This type of behavior usually leads to the end of the relationship.
Few people understand that a cheating partner has nothing to do with them. The person who cheats has their own weaknesses or psychological issues. The cheater is not adult enough to choose the committed relationship or to communicate important needs or wants. They do not have justifications for their actions, and instead they throw accusations at their partner as a way to avoid responsibility. They find excitement and thrills in knowing they are doing something wrong, and they truly believe their choices are blameless.
Saving a relationship with a cheating partner is much the same as bailing out a sinking ship. The reasons people cheat are very complex, and change is often too difficult for people to make a true commitment. Leaving a partner that cheats is the best way to find a better life with a stable relationship. The person who has been wronged in this manner deserves a partner that will stay true to their commitment.