Sex File: What can I do about my partner's worrying fantasy?

It is undoubtedly your excellent sex life and your happy relationship that have given her the confidence to share her curiosity about watching you having sex with another woman

Anything that feels sexually taboo or risky increases adrenaline levels, which in turn speeds up your heart rate and increases blood flow — physiological markers that are identical to the early stages of sexual climax.  Picture: iStock 

My partner and I have been happily together for five years and have a great sex life. I've had many more partners than she has and she recently told me that she fantasises about watching me having sex with another woman. Should I be concerned?

The historic sexual "experience gap" is a red herring. You've been having sex with each other for five years, so she is now as experienced as you are.