By Nathan Gershfeld, co-host of the Beat Your Genes Podcast, Episode 4
If you are four or five months into a relationship and something feels off, but you can’t bring yourself to leave, you are not broken. You are running a Stone Age algorithm that is doing exactly what it was designed to do, in the wrong environment.
That was the through-line of Episode 4 of Beat Your Genes. I brought a question to Dr. Lisle that I hear in different forms all the time: why do so many women stay in relationships they already know aren’t working? His answer pulls back the curtain on one of the most costly instincts built into the female mind, and one of the most common traps that catches decent men on the other side of it.
Your “Heart vs. Head” Conflict Is Actually Two Computations
Before Dr. Lisle got to the relationship trap, he reframed something most people get wrong. For thousands of years, philosophers have talked about a conflict between the heart and the head. Dr. Lisle says there is no such thing.
What you are actually experiencing is two contradictory computations inside the same system. Your brain takes in sensory data, analyzes what the situation means for you, generates feelings attached to that analysis, and moves you toward behavior. When people say their heart is fighting their head, what they really have is two different sets of thoughts, each producing its own set of feelings, each pulling toward a different action. You can only do one of them, so the nervous system has to pick.
That internal battle is what we feel as stress. When the values on both sides are very close, we get cognitive dissonance. The path gets muddy. We are not sure whether to go left or right.
This matters because the next part of the conversation, about women staying in the wrong relationships, is a textbook case of this kind of dogfight. One set of circuits is reading the man correctly. Another set of circuits is reading an environment that no longer exists.
Meet Sarah and Harvey
Dr. Lisle walked through a scenario I want every woman listening to hear. A 22-year-old woman, call her Sarah, meets a guy named Harvey. He is more into her than she is into him. They start sleeping together. She is using birth control and feels responsible, and things seem fine.
Then, four and a half months in, things shift. Harvey starts showing characteristics she hadn’t seen early on. He is more selfish than she thought. He is short-tempered. He is irritable. Maybe he is possessive. Maybe he is distant. Whatever the flavor, she is picking up clear signals that this is not a great match.
Her modern brain knows this. So why can’t she leave?
Because she doesn’t have a modern brain. She has a Stone Age brain. And her Stone Age brain has been tracking the fact that she has had sex with this man maybe 30 or 40 times over three months. In ancestral terms, that almost certainly means she is pregnant. And if she is pregnant, her best bet, by a mile, is to keep Harvey invested in whoever she is carrying. So her attachment circuits flood her system with a message: don’t leave this man, you are vulnerable, he is the most invested father you are going to get.
Dr. Lisle calls this the Last Man on Earth Syndrome. The nervous system acts as if Harvey is the last man she will ever find, and it will keep her stuck long past the point where her happiness, and her actual interests, are telling her to go.
Dr. Lisle’s Rule: If You’re Ambivalent 3 to 5 Months In, Get Out
I asked what he tells the women he sees in his practice. His answer was blunt.
If you are three, four, or five months into a relationship, and it is not feeling good, and he is selfish or inattentive or possessive or difficult, get out. Get out, get out, get out. He said it that way on the show.
He also said he understands exactly what the woman is feeling in that moment. The pull, the anxiety, the sense of attachment. He tells them plainly: those feelings are prescriptions passed down by your genetic code to protect you from single motherhood in an environment of scarcity. You are not a single mom. You are using birth control. You are not in an environment of scarcity. Don’t believe those signals. The other signals, the ones telling you this is not the best deal you can make, are the ones to listen to.
His operating rule is simple. When a relationship is good, you know it. When it’s not good, you also know it. Dissonance itself is information. Relationships are enormously expensive in time and energy. If the payoff isn’t obviously there, your best move is almost certainly to leave.
The Biological Clock Makes the Trap Worse
I asked about the 36-year-old version of this. She has invested years. The biological clock is ticking. She is getting clear signals that he is not Mr. Right, but she is scared to start over.
Dr. Lisle’s position was clear. Every situation is different, but gritting your teeth, forcing the relationship, getting married, getting pregnant, and hoping it works out is a prescription for a mediocre existence. He noted that more than one of his clients, without his encouragement, ended up choosing sperm donors and raising children on their own. He described their lives as much less complicated than the alternative. They ended up with children who were half their genes, full ownership of the parenting, and, importantly, a position of power in any future romantic relationships. Not easy, but often better than forcing a bad match.
The Good Guy Trap: Why Nice Men Fall Into This Too
Women are not the only ones running counterproductive Stone Age software. Dr. Lisle described a matching trap on the male side.
Men have two mating strategies, what Dr. Lisle calls true love strategy, or pair bond strategy, and casual mating strategy. The wrinkle is that early in a pursuit, men have a self-deceptive mechanism that makes them genuinely believe they are playing pair bond strategy when they are not. A man gets excited about a woman, elevates her virtues in his own mind, spills signals of total investment, and fully believes every word coming out of his mouth. Dr. Lisle’s phrase for what gets unlocked in this state was direct: a bunch of male bullshit, and the man has no idea it is bullshit.
A few months in, reality reasserts itself. He sees things he didn’t see before. He is not as into it. But by then, his own conscience can nail him to the wall. And she, thanks to the Last Man on Earth Syndrome, is now deeply attached. Two people, two traps, one mess.
This is the Good Guy Trap. Dr. Lisle’s advice to men, especially conscientious ones: know this mechanism exists in your head, and be willing to chew through the rope three or four months in if you are no longer feeling it.
The Two-Parent Home Myth, and Why Relationship Survival Isn’t the Goal
Dr. Lisle took aim at a sacred cow in 20th century psychology: the idea that the survival of a relationship is inherently a good thing, and that children always do better in two-parent homes. He called the first idea insane and the second one unsupported by the actual research.
He pointed to the work of Robert Emery at the University of Virginia. The research that claims two-parent homes are always better tends to be poorly done. What actually hurts kids is watching constant acrimony between parents. Two parents who have split and minimized their conflict can produce perfectly healthy outcomes.
The practical takeaway, in Dr. Lisle’s words, is that honoring your feelings is not selfish. It is the system working. He tied this back to Nathaniel Branden and the idea of honoring the self. Your feelings are signals. When social institutions and expectations pressure you to override them, no good comes of it.
What to Do With This
Three things stuck with me from this episode.
First, the pull you feel to stay in a relationship that isn’t working is often the loudest signal that you should be paying very close attention to the quieter ones. Dissonance is data.
Second, three to five months is the danger zone. That is when the Last Man on Earth circuit starts firing hard for her, and the Good Guy Trap starts tightening around him. Know what your own nervous system is doing.
Third, the survival of a relationship is not the prize. Two people’s genuine, ongoing happiness is the prize. If that isn’t present, the structure around the relationship is not worth preserving for its own sake.
Listen to the Full Episode
This is Episode 4 of the Beat Your Genes Podcast. Dr. Lisle covers everything in this post in much greater detail in the audio.
Apple Podcasts: https://podcasts.apple.com/us/podcast/beat-your-genes-podcast/id1137772216
Spotify: https://open.spotify.com/show/6TsmRx1vmGL88ORlcXd3PV
beatyourgenes.org: https://www.beatyourgenes.org
Have a question for Dr. Lisle? Submit it at beatyourgenes.org and it may be answered on a future episode.
Beat Your Genes is an evolutionary psychology podcast co-hosted by Nathan Gershfeld, D.C. and Dr. Doug Lisle, PhD. It applies the science of evolutionary psychology to everyday questions about happiness, relationships, motivation, and self-esteem. Dr. Lisle trained at Stanford and the University of Virginia and has over 30 years of clinical experience. Nathan Gershfeld is the founder of Fasting Escape.