It came as no surprise to me when Jill, an acquaintance of mine, told me that, occasionally, she had amorous thoughts about a man at her gym. I didn't for one minute think that she was about to run away with him. She has a lovely husband, two children and a great job, so my response was blasé. “Oh, really?” I asked her.

You'd be surprised at the number of people who lust after someone else while they are in a relationship. Some let it go at that, having entertained only passing thoughts about the other person; others, however, will start to take their relationship for granted and focus their attention on the object of their desire.

Either way, it does not necessarily mean that they are going to start an affair with that person. But it doesn't stop them from entering into a secret fantasy world. For example, my client Tessa had sought my advice in relation to a career issue, but during our session she mentioned that she often thought about an attractive colleague. She said she wasn't too troubled by it because she loved her partner, but wondered whether it might be an indication of any subconscious doubts she might have about him.

After discussing this, Tessa felt reassured. We talked about how her interest in her colleague was fairly normal, and it was something that most people had experienced at some point. I believe it all boils down to biology; as long as we have sexual energy, we may remain curious about anyone whom we perceive to be a potential partner.

For most of us with a partner at home, it's a mildly diverting daydream that we have no intention of turning into reality. The problems, however, begin if you allow it to develop. If you start to experience those tingly feelings of excitement whenever they cross your path, or if you start to flirt with them at every opportunity, that's probably a warning sign that your daydreaming may be taking a dangerous turn.

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