Catherine wanted to tell me "how it felt being the wife in such a situation".
She was driven to issue an ultimatum to her husband of 30 years over his close friendship with a female colleague.
"It was a very loving, natural and unconscious action, but not something, in my view, that you would ever do with 'just a close friend'.
It is an action that is at once tender and sensual and gives a clear sexual message." Catherine and her husband spent the next week being uncomfortably honest with each other.
"My answer to Derek's question – is it possible for a married man to have a deep friendship with another woman?
– is that it is very selfish, dangerous and, yes, I think, wrong to have a deep and affectionate friendship with a woman other than your wife because, as he admits, the sexual agenda is always there.
I really don't think you can have a wife and a 'good friend' as well.
I assumed that we would always be the very best of friends, and would support each other in whatever life threw at us." When the man's wife became ill and died, Tessa was his emotional support.
"I allowed him to offload his distress and gave him comfort, both in person whenever I could, and on the phone if he needed me." So Tessa was shocked and devastated when, within a few months of his wife's death, her best friend announced that he was in a full sexual relationship with another woman, and wanted to cool their friendship.
He made me feel special and would tell me how lovely I looked (my husband is not the best at that).
Time with my friend was magical, and I looked forward to seeing him, and to his phone calls and text messages.