It is harm. The guy could have gone out with a friend, or worked on a hobby, or gone to help his parents with something. Maybe he has a part time job and declined to work a shift because he had this date scheduled. I assume he had to spend money to go to the location where they had the date, so he is out gas money/cab fare/public transportation fare. On top of all that, it’s humiliating to go into a situation expecting one thing and then getting something else. Sure, he isn’t physically harmed, but there is emotional, social, and financial harm.

And again, if someone has shown that they do not respect you, you owe them no courtesy