The key inserts, but doesn’t turn. You think you are at your door, but the key isn’t working. Takes a second or two for the “does not compute” circuit to switch on, but right about then, “her” door swings open and some dude is standing there.
Tragic, but lots of people have tried to put their key in a car just like theirs, or as someone else said, distracted in a cell phone, steps off the elevator on the wrong floor and goes to the second door on the right. And unless the guy came out the door aggressively (haven’t heard a hint of that) sounds like she panicked.
Sad all around.
The lock has a flashing red light if wrong key fob is inserted.