I don't think model railroading really plays any role in folks relationships, I think its more a matter of one spouse supporting their other half. My wife supports my model train hobby and I support her many, many () crafting hobbies. I don't understand all of her hobbies and she doesn't necessary understand mine, but we support each other anyway.
We will have our 29th Anniversary in two weeks and are looking forward to the next 29.
Jim