Date: __/__/____ (date)
Dear __________ (name),
Hello, my dear brother, I hope you are doing good. I am also good here.
I wish you a very happy Raksha Bandhan. You know I am missing you a lot on this day and I wish that you could be here with me so that I would tie Rakhi on your hand. Also, everybody keeps asking about your health. I understand why you didn’t come this year. I hope we will meet soon.
Please take good care of yourself.
___________ (Your name),
___________ (Contact details)