That scene with her and Gerry....

I was wondering if someone could explain the scene where she and Gerry were laying on the couch with a bunch of candles. It looked like they had dinner and were finishing up watching a movie. And she says "It's been almost 2 months since I've done that, almost to the day". And he says to her "Don't be daft, what are we a survey?"
Well, I was wondering what she was talking about-and what was that movie they were watching?