[Your letterhead, if desired; if not, your return address]
[Date of letter-month, day, and year]
[Recipient's first and last names]
[Street or P.O. box address]
[City, State ZIP code]
Dear [recipient's name]:
I really regret that argument we had yesterday and want to apologize to you for anything I said that hurt your feelings or upset you. It makes me sad to know you're sad about things. I would really like to have a long conversation so we can both get things out in the open and resolve everything. Can we do this?
You are my everything, and I want us to right any wrongs and get back to having the incredible relationship that both of us really want.
All my love,
[Sender's first and last names]