At that moment of vulnerability, if "someone comes along that says 'You're gorgeous and wonderful' and makes you feel a hell of a lot better than your marriage is making you feel," it can be easy to fall into an affair, Lusterman says.
"Often the attraction is not to this person, but to the way unfaithful partners experience themselves in the affair: the attention, the adulation, the excitement," Spring says.
"At some point [the cheater often] realizes that the affair won't work, and they come back to the marriage," according to Lusterman.
Unfortunately, this wake-up call often occurs after the cheater gets caught.
Often, cheaters don't take into account what Danine Manette, criminal investigator, infidelity expert and author of "Ultimate Betrayal" calls the "X factor."
The X factor is the unknown reaction of those the cheater hurts in his or her transgression.
Cheaters get caught up in the thrill of the affair and fail to realize the impact their actions will have until it is too late, Manette says.
The "hurt parties," as Spring calls them, often feels "crazy, helpless and alone" after an infidelity, and the result of these emotions can be more than just emotionally damaging.
As a criminal investigator, Manette sees the repercussions of the X factor daily, whether as property damage from a jealous lover or a double-homicide -- as she is working on currently.
"I see the seedy side of infidelity ... fights, tearing up the car of the other woman, [or] trying to run someone over," Manette says.
Referring to the rumored physical violence between Tiger Woods and his wife, Elin Nordegren, following the discovery of the affair, she points out "if she did chase him with a golf club, the fact that he didn't retaliate keeps this case off my desk."
And even if the situation doesn't turn violent, the healing ordeal -- especially for the hurt party, is a long and arduous road, experts say.
"A burnt finger remembers the fire," Manette says, "when they look you in the eye and lie to you over and over again, effortlessly, it makes you question your entire reality. You carry the [suspicion of infidelity] ... whether warranted or not, to new relationships."
"It takes a lifetime to build trust, a moment to tear it down, and about another lifetime to rebuild it," she says.
"There's no easy way to move on -- you can only move through the trauma," Spring says.
The decision to stay has to be a "thoughtful, self-interested decision for both people," she explains.
"There has to be tremendous remorse, but remorse is not enough," Neuman adds.
"If couples are going to rebuild their marriage, the unfaithful partner [must be] willing to look deeply into themselves and understand why they cheated so when they say I'll never cheat again. It's not just a verbal reassurance," according to Spring.
All this, of course, is assuming that the hurt party is willing to stick around.
In the case of Tiger and Elin, it looks like remorse may not be enough to save their marriage.
Tiger has apologized publicly multiple times, and in a statement last week he said he needed to "focus [his] attention on being a better husband, father and person."
But after reports of Nordegren consulting a divorce lawyer, a source close to Nordegren told ABC News that "the divorce is 100 percent on."