Pretty much everyone in this thread is being dumb. The solution to your problem is this: talk to him. Literally just pick up your phone right now and text him - “hey, when we went out for coffee, ummm… I feel awkward asking this, but, was that a date?” If he says no, apologise for assuming and continue enjoying his company as a friend. If he says yes, tell him you like him as a friend and appreciate his interest, but that you aren’t interested because you are moving to a different city.