GreatAspirations: You’re right, the way it was said made he difference. One way says you’re not interested in him opening the door at all, one says in this specific case, you’re trying to help him out.
As for after marriage, true, I don’t always open the car door or other door for my wife, but I still do it many times. Holding open a regular door happens more often, and I get a smile and a thank you. When I open the car door for her, her face really lights up with a smile. I don’t do it every time, because I don’t want that to fade. It’s also difficult when we’re each strapping a kid into the back seat.