Apparently, randomly cancelling your flight and not telling you about it is SOP for Alaska:
Alaska Airlines Cancels All Your Wedding Guests’ Flights, Forgets To Tell You
There's one thing that doesn't make sense in the story (well, several things actually, but one really glaring one): despite arriving only 45 minutes before their scheduled flight... it says that at 25 minutes before scheduled departure, they were told they'd already missed the flight?? So... the plane left EARLY? And somehow it's THEIR fault for missing it?