Is Fantasizing Cheating? The Science of Erotic Imagination

It’s possible to honor your desires without shaming yourself or your relationship.

A client once asked me: “Is it okay if I fantasize about things my partner isn’t into? I find myself fantasizing about things I used to do and enjoy, but there is no way that I would be able to do things in this relationship.”

If you’ve ever wondered the same, you’re not alone. Sexual fantasies are a normal—and vital—part of human erotic life. But when your fantasies don’t align with your partner’s interests or comfort level, it can bring up questions about desire, loyalty, and whether your imagination is betraying your relationship.

In this blog, we’ll explore:

• Why we fantasize, according to sex research

• What it means when your fantasies differ from your partner’s desires

• The paradox of eroticism and why our hottest fantasies often involve the forbidden

• How to hold space for your erotic imagination without shaming yourself—or your relationship

  
  

And if you'd rather watch than read, feel free to check out my YouTube video on this topic!

Why We Fantasize: The Science

Justin Lehmiller, PhD, in his groundbreaking book Tell Me What You Want (2018), surveyed over 4,000 Americans about their sexual fantasies. His research revealed that nearly everyone has fantasies, and most people’s imaginations don’t perfectly match what they act out in their relationships. In fact, only a small percentage of fantasies are ever shared—let alone enacted—with a partner.

So why do we fantasize? Lehmiller explains that fantasies serve several functions:

• Exploration: They let us try on new roles, scenarios, or sensations without real-world risks.

• Enhancement: They amplify arousal, making partnered sex (or solo sex) more exciting.

• Coping: They can relieve stress, escape routine, or help us feel a sense of control.

  
  

This means your brain is doing something perfectly adaptive and healthy when you drift into a fantasy—whether or not your partner shares it.

The Paradox of Eroticism

Jack Morin, PhD, in The Erotic Mind (1995), describes what he calls the paradox of eroticism: the very things that excite us most are often wrapped up in tension, taboo, or the sense that something is just out of reach.

Think about it. How many fantasies are hot precisely because they break a rule—whether that’s being more dominant, more submissive, or imagining a situation that feels unlike your day-to-day life? According to Morin, this tension between risk and safety is what gives eroticism its charge.

When you fantasize about things your partner isn’t into, it doesn’t necessarily mean something is “wrong” with your relationship. More often, it reflects this paradox: your erotic mind is curious about experiences that exist at the edges of your comfort zone.

Fantasies don’t equal betrayal. They’re proof of your erotic mind at work.

Desire Is Not a “Drive”

Part of the confusion comes from the myth of the “sex drive.” Many people think of desire as something biological and automatic, like hunger or thirst. But as research shows, that’s not accurate.

As I explain in my teaching and content, desire is not a drive—it’s an incentive-motivation system. In other words, our desire is shaped by context, meaning, and the presence (or absence) of incentives.

That’s why fantasies often become the fuel that lights the fire. They’re not proof of a broken libido; they’re an example of your erotic brain doing what it was designed to do: create meaning and excitement around sex.

When Fantasies Clash With Relationship Realities

Here’s the tricky part. You might find yourself fantasizing about scenarios your partner simply isn’t into. Maybe it’s a kink they don’t share. Maybe it’s something from your past you know isn’t possible in your current relationship.

This can create a desire discrepancy—not just in frequency or style of sex, but in the very content of what turns you on. And that can stir up guilt, shame, or even resentment.

So, is it okay to fantasize about things outside your relationship? The short answer: yes. Fantasizing is not the same as cheating. But the longer answer is about how you relate to those fantasies—and how (or whether) you share them.

Three Questions to Ask Yourself

Before rushing to share every fantasy with your partner, pause and reflect:

1. What need does this fantasy meet for me? Is it about novelty? Power? Being desired? Knowing this can help you understand your erotic wiring.

2. Is this fantasy essential to my fulfillment, or just one of many things that turn me on? Some fantasies are “core” (deeply tied to identity), while others are situational (fun, but not necessary).

3. What am I hoping for by sharing it? Validation? Permission to explore? Simply feeling seen? Being clear helps prevent disappointment.

Take a moment of self-reflection to understand the needs behind your fantasies.

The Role of Fantasy in Long-Term Desire

In long-term relationships, desire naturally ebbs and flows. Researcher Rosemary Basson’s model of responsive desire reminds us that many people don’t feel turned on until arousal is already underway. Fantasies can act as a bridge—helping you “preheat the oven” by mentally creating conditions for arousal.

Couples who talk openly about fantasies—without pressure to enact them—often report higher satisfaction. Even if a particular act never leaves your imagination, acknowledging your erotic world can make you feel more alive and connected in your partnership.

How to Navigate Mismatched Fantasies

1. Normalize the conversation. You don’t have to dump every fantasy on the table at once. Instead, you might say: “Sometimes I imagine things that I know aren’t realistic for us. It doesn’t mean I don’t love what we have—it just means my brain gets creative.”

2. Distinguish between fantasy and reality. It’s okay to enjoy a fantasy that you never plan to act out. Many people keep these private, like their own internal erotic movie theater.

3. Explore overlap. Maybe your partner isn’t into the exact scenario, but is there a way to capture the essence of the fantasy—power dynamics, role play, novelty—within your shared comfort zone?

4. Build safety through honesty. If you decide to share, do it gently and without expectation. The goal is connection, not coercion.

Gently sharing a bedroom fantasy will create space for curiosity and connection

When to Seek Support

Sometimes fantasies highlight deeper struggles:

• Shame or secrecy that makes you feel broken

• Relationship resentment (“I can’t get what I want here”)

• Trauma triggers that show up in fantasy form

  
  

This is where therapy can help. As a licensed marriage and family therapist and AASECT-certified sex therapist, I work with individuals and couples to unpack desire differences, heal from shame, and create intimacy that feels authentic.

Key Takeaways

• Fantasies are normal. Everyone has them, and most don’t align 100% with their partner’s desires.

• They serve a purpose. Fantasies enhance arousal, provide novelty, and allow safe exploration.

• The paradox of eroticism is real. Our hottest turn-ons are often linked to taboo or tension.

• It’s okay to keep some fantasies private. You don’t have to share or enact everything to be healthy.

• Open communication builds intimacy. Talk about fantasies in a way that fosters curiosity and connection, not pressure.

References

• Lehmiller, J. J. (2018). Tell Me What You Want: The Science of Sexual Desire and How It Can Help You Improve Your Sex Life. Da Capo Press.

• Sexual Health Alliance. (n.d.). Justin Lehmiller: The Science of Fantasy.

• Morin, J. (1995). The Erotic Mind: Unlocking the Inner Sources of Passion and Fulfillment. HarperCollins.

• Singer, B., & Toates, F. (1987). The sexual motivation system. In Handbook of Psychobiology. Academic Press.

• Basson, R. (2000). The female sexual response: A different model. Journal of Sex & Marital Therapy, 26(1), 51–65.

About the author

Dr. Holly is a leading expert in sexual health based in Orange County, certified as both a clinical sexologist and AASECT sex therapist. With extensive experience in sex therapy, sexual wellness, and relationship counseling, Holly provides evidence-based insights to clients in Orange County, the state of California and beyond. Recognized for expertise in sexual trauma recovery, sexual dysfunction, and intimacy, Holly is dedicated to empowering individuals with practical advice and research-backed strategies. For more, follow Holly for expert advice on sexual health and relationships.

Visit www.thehollywoodsexologist.com to learn more and request a consultation.