Years ago, I'd heard that if a couple can go on a ride for twelve hours, or something to that effect, and not stop a conversation, then it's a pretty solid relationship.
A few years ago, my wife and I had a number of events to attend in our province, which required several long distance trips, within about a month's time frame. And we talked. And talked. On each and every trip.
I can forgive the last hour of the trip home, for no other reason than our voices gave out.