Are you sure your wife didn't hide the key so she can take the boat out while you're gone?
They normally come with two keys.
I've put it in a safer place.
Well, you'll never see that again
I was waiting for that!
My suggestion is to immediately go to any shop that cuts keys and have a handful made. At about a buck a piece it beats not having any when you really need one. One of those spares should be hidden somewhere in the boat.