While many intimacy-related fantasies are harmless forms of imagination, experts warn that indulging in a certain one — admitted by more than half of married people — can lead to the “inability to be present with current partners” and even becoming “emotionally stuck”.

Fantasies can serve as a creative mental space where people explore ideas, desires, and scenarios that may not align with their real-life actions. They might involve playful curiosity, role-play, or simply revisiting moments of intense emotional connection. According to research by The Myths of S:ex author Justin J. Lehmiller, some of the most common intimacy fantasies include multi-partner scenarios, voyeurism, and cosplay.

However, one particular fantasy — confessed by 55% of married individuals — is drawing concern from relationship specialists: imagining moments of intimacy with an ex.

The Ex-Fantasy That’s Causing Concern

A number of Reddit users have openly shared their experiences with this fantasy, revealing that it can become surprisingly consuming.

One user admitted, “It’s not like I’m desperate to get back together with him, I already blocked him and got rid of everything that reminded me of him. But the memories are still there. And as much as I try to get rid of them, I can’t. Every time I think of them, I still get butterflies.”

This sentiment resonated widely, with others commenting:

• “Not going to lie I do the same with my ex… I think about her daily.”
• “I do it all the time.”
• “Yo, I felt this.”

The sheer number of similar admissions suggests this is not an isolated behavior.

Why Our Brains Hold On to Old Flames

Relationship expert Anita Fletcher explains that “our minds don’t operate on a strict timeline when it comes to desire and memory”. The brain is wired to store emotionally charged and physically intense experiences — which is why memories of intimacy with a past partner can resurface unexpectedly.

“It doesn’t necessarily mean you want them back,” Fletcher adds. “It’s about revisiting familiar feelings of desire and pleasure.” In some cases, this can be harmless nostalgia. In others, it can signal deeper emotional attachment to the past.

When the Fantasy Becomes a Problem

While occasional thoughts about an ex are normal, Fletcher warns that the danger lies in obsession, constant comparison, or the inability to be fully present with a current partner.

Warning signs include:

• Using ex-related fantasies as the only reliable way to reach pleasure.
• Feeling emotionally unsettled or sad after such fantasies.
• Struggling to connect intimately with a new or current partner.

If these patterns emerge, it may be a sign that unresolved emotions are at play. Fletcher recommends “expanding your imaginative repertoire” — shifting focus to new scenarios, sensations, or even fictional characters to help break the cycle.

“Instead of feeling guilty about ex fantasies, use them as a clue to understand what you find appealing,” she advises. “Then you can communicate those preferences to a partner in the present.”