This is more for you couples living on border towns.

I have a friend in Detroit getting married around the time we think Mary will get her visa. I was thinking she could drive to Windsor from Toronto, and I would drive to Detroit from Chicago. I'd cross (using nexus) and pick her up. We'd leave her truck somewhere safe for the night. I'd cross over for the wedding with her (not nexus) and explain the situation. The next morning I'd cross back into Windsor to drop her off (not nexus) and just pull a quick U-turn back to Detroit and blast thru the nexus lane.

Is there anything wrong with my plan? Are any of the border officials going to get weird with me about making so many trips back and forth?

They shouldn't. People do it all the time.

The problem you *may* have is with getting Mary over the border. But probably not. Just bring the wedding invitation with you, they may ask for it.

Yep - she'll probably still have ties right? Get her work to write a letter indicating they know she'll be away from X to x and that she's returning to work on X. My immediate teamlead did it and put her name and office number too

I'd say that it's possible for your fiance to join you, but be prepared to show ties to Canada (apartment lease, utilities bill, letter from employer). Enjoy the wedding!