Colleen, that's a more common problem that I bet you think!
All you have to do is remove the relationship between the wrong people. If there are other profiles connected to the person you're removing (like spouse, children, etc.) that do belong to that person, then you can just leave them alone and there will be a single profile or a small family unit of profiles floating around not connected. Someday, someone will show up and discover that they're his/her family and claim them to add to the rest of his/her family.
I gather it's the wife that's incorrectly connected - just edit either profile and click the edit marriage link, then at the bottom, there will be a button to remove the spouse - do it and that's all it takes!