The goal of a cheater is to (hold onto all that is good) in their "primary relationship" while addressing their other needs on the side.
Most cheaters don't want to go through a breakup or divorce.
They have no desire to "replace" one relationship with another. Simply put they refuse to buy into the 80/20 rule which states at most anyone you settle down with is only likely to be able to give you 80% of what you desire. (That's if you're lucky.) The cheater insists upon having all 100% of their needs and desires met.
I believe there are 3 basic cheaters
1. The Incessant Cheater
This person bores easily and is always looking for the excitement and thrill that comes with being with someone "new". They love to flirt and tend to be outgoing. Their motto: "Variety is the spice of life". There is nothing you can do to become "new" again.
2. The Unbelievable Opportunity Cheater
This person unlike the incessant cheater is NOT "proactively" looking to cheat. They may have a secret crush on someone or a person whom they consider to out of their league suddenly comes onto them, a platonic friend initiates affection during a difficult time, or a fantasy could become a reality.
This type of cheater caves in to temptation. It's not unusual for them to confess weeks, months, or years later if the guilt becomes too much for them each time they look into their loving mate's eyes.
3. The Discontented Cheater
This person blames YOU for why they had to step out of the relationship! You stopped being the person who won their heart or you "changed". Maybe there has been more complaints than compliments, less or no sex, neglect, they feel taken for granted. Someone comes along and makes them feel "special" again, flirts with them, or massages their ego. It doesn't take much for stranger to put a smile on the face and in the heart of a unhappy person.
Out of the three types of cheaters this is the one where a (betrayed person) may offer forgiveness if they buy into the belief (their) actions led to their mate's poor judgment.
What Keeps Most People From Cheating?
1. Being "in love"
2. Not wanting to risk losing that "special someone".
3. Imagining how hurt (they'd feel) if their mate cheated on them.
Whenever a couple transitions from thinking in terms of "Us & We" to "You & Me" there's a good chance they're likely to make "individual needs" their top priority.