A foreign friend of yours plans to visit your place and stay with you, but you are not available on that date. Give your friend another alternate date for the visit.
In your letter, you should:
-apologize for it
-explain what you are doing on that date
-suggest to him/her an alternate time to come.
Hope this letter finds you well. I’m writing to follow up on your plans to visit to RD, and I want to apologize, because I will be out of the country, and won´t be able to stick to our plan. I’m really sorry!
As you know, I was recently hired as a Digital Marketing Specialist for a real estate company, and as part of my training they are flying me over to New York, where I’ll meet Ryan Serhant, an industry guru, to learn everything related to paid advertising and the latest trends.
I will be back two weeks later, though!… And since you’re staying for the whole summer we will still have plenty time to go out and share together. I will be back on Sunday the 22nd; if you arrive in the afternoon I’ll be there to pick you up; I promise you we will have a wonderful summer! You will enjoy our gastronomy, the culture, our people, our art, the landmarks, the nightlife, our beaches with white sand. You will enjoy everything!
So sorry again for any inconvenience, but the truth is that I can’t wait to see you.