Apology Letter For Flaking
Dear {Recipient},
I'm sorry for flaking out on you {yesterday/last night}. You know I hate backing out on my commitments.
Unfortunately, {reason}, so I had no choice but to cancel at the last minute.
I understand if you're upset and don't want to talk to me right now. But I'd like to make it up to you as soon as possible. So if you're free sometime this week, please let me treat you to {a coffee/lunch/a movie}. What do you say?
Best,
{Your Name}