Living together. My future FIL would not come into the apt we had. They would bring things by for their daughter, but he wouldn't leave the car even if I wasn't there. Of course, this was in the 70's and he was a retired Marine colonel. Not that has that much to do with it, but he was pretty straight laced. Laced up pretty tight, too.
Oh well, that marriage lasted 9 years. He had a lot more to worry about after that. Another story.