Even without the added fastening the opening is not likely to have moved even if she puts her arms out wide and pretends to be a windmill

I don't like the dress very much because it is too big and so a bit blah but the colour suits. She has wonderful hair and eyes.
For me it is a bit creeepy though,
the idea that her husband is changing her, influencing her appearance (and I don't believe it).
Maybe he says you look better in that or that colour etc. My mother used to try and push my hair style - the last time I agreed was when I was there - 600 miles away - for the funeral of my father. I absolutely hated it but she said she liked me that way. Never again.
I get the perspective that apart from a mirror you don't see yourself for the rest of the day

?? Maybe he has better dress sense than her mother does and gave her some guidance