Dear Camilla Duffey
Sometimes it is true.
There is a theory to explain this. People who spend a lot of time together tend to copy each other's facial expression. It's a thing that humans do (without even realising it) to help them get on well with each other.
So people who have been married a long time have probably spent a lot of time copying each other's expressions. This will mean that some muscles in their face will be exercised more than others. As those muscles stay firm and other muscles get weaker they will change their size and shape to match. So the shape of each person's face will gradually start to look a little more like the other's.
I quite like that theory. I wonder if it's true.