Infidelity is a heartbreak no one should ever have to deal with, but when it happens, most couples are left with haunting questions. No one situation can be placed in a tidy box of reasons, but if you and your husband were happily married when he had an affair, these can explain how this happened.

He's covering up insecurities

Your husband is likely a great spouse. And as a great spouse, he might feel a lot of pressure to make sure you and everyone else in the family is happy.

But deep down he could be suffering.

Is work overwhelming? Does he feel like it's impossible for him to succeed as a parent? Is he remembering unresolved insecurities from years ago?

If he feels a lot of pressure to keep your family happy, he may never feel comfortable revealing those problems, said marriage therapist Aaron Anderson.

"Instead of being able to talk out loud about their insecurities, wants, regrets, etc. they continue on living a life that makes them only superficially happy," he said. "But they have deeper desires that are going unfulfilled. It's the need to fulfill those deeper desires and their inability to talk out loud about them that makes them try to get them fulfilled in secrecy (e.g. by having an affair)."

It's easier to look for something new rather than talk about expectations

Men don't just need sex; they need emotional connection (just like women). But unfortunately, it's usually pretty painful for a man to tell his wife he doesn't feel appreciated, according to marriage counselor M. Gary Neuman. After all, it's not "manly" to ask for more affirmation.

He will shove those emotional disappointments to the back of his brain and deal with them later.

Ladies, that later is scary. Those emotions will eventually surface, and if he feels more appreciated from a different source, it could be hard for him to resist that validation. Not being emotionally satisfied was the main reason 48 percent of men cheated, according to a study by Neuman.

Cheating makes him less vulnerable to one person

In case you haven't sensed a theme here, emotions play a great deal more into infidelity than we tend to think. For most men, it's super hard to express how he feels - even to himself. (See above)

But marriage is all about being vulnerable to ONE person — which is scary. If he can spread out his life's intimate details between two people, he can feel less vulnerable (and dependent) on one person.

He doesn't know how to balance love with romance

Feeling safe, loved and like you belong is a basic human need, but humans also crave adventure and mystery. Balancing the two in a marriage is hard, according to couples therapist Esther Perel.

When we feel like we belong and our relationship is reliable, routine develops. And there is nothing more opposite of adventure than routine. Sometimes happily married men enjoy the comfort of reliability and love from their wife, but look somewhere else for a thrill.

He didn't mean to

More than half of cheating men felt guilty during the affair. Sixty-eight percent of unfaithful men said they never dreamed they would cheat on their wife. This isn't comforting, but it does show how cautious couples need to be to prevent accidental affairs from sneaking in. Technology makes it pretty easy to develop an inappropriate relationship.

It's NOT about how you look

Please stop comparing, and never belittle how beautiful you are. Your husband did not cheat on you because he wanted someone more attractive. There is no level of makeover you could get that would make a cheater less likely to cheat.

And interestingly, only 12 percent of cheating men were more attracted to their mistress than to their wife, according to Neuman's study. Your beauty has nothing to do with it.

His good friend had an affair

Have you ever heard the phrase, "You are the average of the five people you spend the most time with"? Well, it's true. Seventy-seven percent of cheating men had a good friend who had an affair first. If a buddy your husband respects and loves can justify an affair, your husband might start to view affairs as less damaging than he did before.

Whatever the reason for the affair, the most important thing to remember is that YOU are worth loving. Don't allow your husband's mistake to make you feel worthless. With help, healing can (and does) happen — in time.