What's With the Dress?

For most of the film Trust, Maria is wearing an old-fashioned dress that she dons after Matthew's dad trashes her old clothes. We know one thing about the dress- it was Matthew's mom's. But Matthew is in his twenties at least (the actor, Martin Donovan, was 33 when the movie was filmed), so that means Matthew's had his dead mother's dress in a closet in his house for potentially 30 years. Suddenly Maria comes along, finds the dress, which fits her perfectly, and wears it for the rest of the film. So... why? What's the significance of the dress, and why does Maria never take it off?

One possible explanation is that, by wearing the dress, Maria becomes the replacement significant female figure in Matthew's life. For his entire life, Matthew's mother has been a dress hanging in a closet. When Maria puts on the dress, she brings his mother to life... which sounds super creepy given the fact that he wants to marry her. But it could also contribute to Matthew's attempts to get Maria to keep the baby and raise it with him as a family. Maria, in his mother's dress, reminds him of what his mother could have been to him. He wants to raise the baby with her so that he can experience what his life could have been like if his mother hadn't died giving birth to him.

Why doesn't Maria ever change clothes, though? Even if she was having an existential crisis, you'd think she wouldn't wear the same old-fashioned dress every single day. It seems more likely that she is shown wearing the dress over and over to exaggerate its significance to Matthew and to demonstrate her change in mindset after she meets him. Her repeated wearing of the dress is just there for symbolism, like how every man on the train had a trench coat and pipe, and how tons of cars in the parking lot had the same bumper sticker.