One of things famous people say when they get caught having an extramarital affair
and then have to go public with an apology is they did it because they could. They had the means and the power to make it happen and they took full advantage of the situation.
Whether they are sorry for having an affair is open to debate. It's obvious in some instances they are sincere in their apologizing. Others it is clear they are only sorry they got caught. They are apologizing alright but you can tell from their words and body language that they hate every minute of it.
For some cheating spouses having an extramarital affair may directly correlate to what their significant other is or is not doing within the relationship. That's not an excuse to cheat but a bad marriage can make infidelity more likely.
Still with more than a few people it's all about the ego. Pride comes before a fall and infidelity is the cliff many a cheating spouse tumbles over.
Famous people are not the only ones with oversized egos. Infidelity happens on a daily basis to many people who are nowhere near the media spotlight.
And just like some celebrities they tell themselves it is their right to cheat. Their spouse has failed them in some way so infidelity is justified.
Or someone at work came onto to them. In essence their ego told them "You still got it" and there was no way they were going to turn down what was being offered.
Sometimes it's the other way around. They see someone they are attracted to and no matter what it takes they are going to get what they want. Nothing is going to deny them this pleasure especially some wedding band on their finger.
The conquest may on some level make them feel bad emotionally but their ego is feeling pretty good and that in far too many circumstances overrides anything and everything else.