I am so sorry that you found a stain on the dress I borrowed from you. I should have noticed the damage. Please believe me when I tell you I had no idea it was there. I have been trying to figure out when during the evening I could have dropped wine on your dress.
I hope you will allow me to take you out to lunch, and to your favorite store to buy a replacement. This is the only suitable thing that I can do for a friend such as you.Sincerely