Sex File: My partner’s kinky sexual fantasies are turning me off

"The simplest explanation for the change in your partner's behaviour... is that he now needs stronger stimuli to achieve the same level of arousal and is using sexual fantasy to increase excitement."

Frenzied sexual vigour rarely comes from nowhere, especially in older men, so it's worth thinking about when this all started and what might have triggered it.

I am in my 60s and have been in a relationship with a man for ten years. We have always enjoyed our sex life, but now he keeps wanting to try new things, talking about fantasies of me with other men and women - including a female friend he has history with - which is turning me off. 

Is there a way back to the sex we used to enjoy?