Theory: Were there two Matthews at the End?
Knowing the ending & re-watching it again, I've come to the conclusion that The Matthew who is back at work, following the podded Elizabeth around is the real Matthew. He seems too aware of her & deliberately follows her around, which suggests there's some emotion there, he just can't show it & therefore must live a life cursed w/o being w/the woman he loves.
Then there's a second Matthew, a podded copy of the original, who is the one walking around in the trench coat & who shrieks at Nancy when she calls out to him.
With the copying pods needing to destroy their original host, could this theory even be possible?