Courtesy of David R.
To My Dear Wife,
You will surely understand that I have certain needs that you with your 54 years can no longer supply. I am very happy with you and value you as a good wife. Therefore after reading this fax, I hope you will not wrongly interpret the fact that I will be spending the evening with my 18 year old secretary at the Ritz Hotel. Please don't be perturbed. I shall be back home before midnight.
Your Loving Husband
When the man came home, he found the following letter on the dining room table:
My Dear Husband,
I received your fax, and thank you for your honesty. I would like to take this opportunity to remind you that you are also 54 years old. At the same time, I would like to inform you that while you read this, I will be at the Hotel Fiesta with Michael, my tennis coach, who like your secretary is also 18 years old. As a successful businessman and with your excellent knowledge of math, you will understand that we are in the same situation, although there is one small difference: 18 goes into 54 more often than 54 goes into 18.
Therefore I will not be back before lunchtime tomorrow.
Your Loving Wife