My interpretation
I made an account for the sole purpose of writing this interpretation.
I believe the man in the coat is an ex-lover of the woman in the booth. He looks at the woman and begins crying at the sight of her, happily remarried -- he's no longer in her life, but the way she looks at him implies they were still on good terms and able to fondly appreciate old times. Perhaps the decision to split was mutual (otherwise she would not be smiling), but the man secretly regrets the decision but is too late to rectify the mistakes.
The fact that his hand was bloody before seeing the woman insinuates that he had this entire thing planned out. He knew he was going to get caught, and I don't think he was actually going to fire at the police. Perhaps he wanted the woman to see his death so that, in some way, he could make one last impression. But perhaps things could have turned out differently "IF" he had simply put the gun down and not tried to be a martyr.
The man at the end of the movie is probably the spirit of the man in the coat. Notice how his hand is bare but then acquires a ring -- it's probably to further instill the fact that he used to be her husband.
I could be totally off but that's what I saw -- what's cool about this animation is that it's vague enough to catch interest, but it provides enough information to get your mind going.