Dear Sarah,
Thank you so much for the invitation to your wedding anniversary party next Saturday. It was such a lovely surprise to receive your card, and I was really looking forward to celebrating this special milestone with you and Mark.
However, I am terribly sorry to say that I will not be able to make it. I have checked my calendar, and it turns out that I have a long-standing commitment that weekend. My company is hosting an intensive training workshop that I am required to facilitate, and unfortunately, it is impossible for me to reschedule or find a replacement at such short notice.
I am genuinely gutted to miss out on the festivities, especially since I was eager to catch up with everyone. Could we perhaps arrange a time to meet up the following weekend instead? I would love to take you both out for a celebratory dinner to make up for my absence. Please let me know if you are free on the Saturday after next, perhaps around 7 pm?
Have a fantastic time celebrating, and give my best to Mark.
Best wishes,
Jamie