Unpopular opinion: I feel bad for Betty Draper whenever I re-watch episodes of Mad Men. I understand that she’s hardly up for any mother-of-the-year-esque awards and doesn’t have the best-ever personality, but I don’t understand how she’s supposed to be a villain. I mean, it’s her philandering husband who holds court all over New York (and sometimes California) while she’s unhappily trapped in a veritable suburban cage. No wonder she’s blasé at best, right? But still, the plot lines of that show—a master class in infidelity—have always made me wonder, Why do people cheat? Because if you have a wandering eye, and you’re unhappy in your partnership, it would be better to break up, right?

The truth is, there’s no singular one-size-fits-all reason for cheating, largely because cheaters revel in the broad category of deception. And that fact alone makes trying to pinpoint any kind of catalyzing reason nearly impossible, says sex and relationship therapist Tammy Nelson, PhD, author of When You’re the One Who Cheats. “Infidelity, by its nature, is based on dishonesty, so cheaters aren’t honest about why they cheat—they even lie to infidelity researchers.” As someone who wrote literally the book on cheating, she would know.

“Infidelity, by its nature, is based on dishonesty, so cheaters aren’t honest about why they cheat—they even lie to infidelity researchers.” —sex and relationship therapist Tammy Nelson, PhD

Still, she has several hypotheses to offer as to why people might be disloyal. Using these, you can examine—if you’re Betty Draper in this scenario—whether it’s worthwhile to stay in your relationship when infidelity hits.

Why do people cheat? Check out 3 possible reasons below:

1. They find the very nature of cheating to be sexy

“It is clear that one reason people have affairs is simply the forbidden nature of cheating,” Dr. Nelson says. “People like the feeling of doing something wrong.” One study published in the Journal of Personality and Social Psychology found that this is actually referred to as a “cheater’s high” (appropriate). In the study, more than 1,000 people from the United States and England were surveyed about how they felt committing certain misdeeds, such as cheating on a test or logging in extra hours at work. Results showed a correlation between acting unethically getting a significant emotional boost.

Big caveat, though: Doing something wrong only felt good to the participants if they didn’t get caught.  Humans are still hardwired for empathy (or really just don’t love being found out), and those feelings can quickly turn negative when someone is actively in the know about and hurt by the misdeed.

2. It can satisfy fulfillment gaps

People have their own needs, and when they feel like those aren’t being fulfilled, they may become compelled to step out of line. “They want to stay in their marriage, and an affair supplies them with just enough of what they are missing to allow them to stay with their partner,” Dr. Nelson says. It’s why constant communication about what your needs are is essential to being in a healthy, monogamous relationship (although also essential is like, not cheating).

There are so many complicated levels to that, and one way many end up hurt is subscribing to the belief that they led their partner to cheat. So, if you’re the one who cheats and you get caught, Dr. Nelson strongly advises that you never even hint at putting the blame on your partner.

3. They’re trying to escape themselves

“The bottom line is that most people who cheat are not looking to be with someone else; they are looking to be someone else,” Nelson says. “To feel like a different person.” If someone feels pressured and unhappy about the responsibilities of certain roles (husband, wife, father, mother, partner), it could be alluring to link up with someone who injects a sense of danger after-hours. For instance, PTA meetings and a no-nonsense spouse may make you feel old, but you can escape your fears of aging by…having an affair with your kid’s wacky teacher! Or a beatnik artist! Or a strong-willed department-store owner! Or your neighbor! Or a…waitress or…someone….

Things really got exhausting on Mad Men by season seven, but I digress.

To this point, it’s very important to apply the “it’s not you, it’s them” rule if you find yourself in Betty Draper’s shoes. But what to do next, after you absolve yourself from any feelings of blame, can be trickier to understand.

How do you know if the relationship is worth salvaging?

Even if we can understand why people may cheat, it certainly doesn’t excuse the act. When you learn that your partner has been having an affair, you’re about to have what Dr. Nelson calls a “wake up or break up” moment. This means, she says, you have to choose to either break up or wake up and tackle your relationship problems directly. If you go with the wake-up option, she recommends no detail be spared when it comes to describing the affair.

“Couples are more likely to stay married after an affair when they thoroughly discuss what and how it happened,” Dr. Nelson says.

And if you choose to break up? More power to you. An affair was ultimately the breakup catalyst for the Drapers, although (plot twist) it had nothing to do with Don and his rotating door of paramours.

Learn the key differences between micro-cheating and micro-flirtation. And if you suspect that your partner is cheating, the signs are probably visible all over their stupid face.