Dear …

Please accept my deepest apology for missing your __(type of event)__. Regrettably, __(unforeseen circumstances or briefly describe reason)__ prevented me from attending. I want you to know, though, that I was thinking about you and __(name/the others/etc.)__ the whole time, wishing I could be there. No doubt, I missed out on a wonderful __(day/evening/etc.)__.

I genuinely hope that that your __(type of event)__ was a smashing success and that everyone had a good time. I’m sure __(your dinner was scrumptious/your were a beautiful bride/etc.)__, __(Name)__. The next time we __(get together/talk)__ I am really looking forward to hearing all about it. Again, my sincere apology for not being able to share it with you.

Kindest regards,