In an ideal world they both keep their own separate quarters and just use which ever one is preferred for hanging out drinking tea based on layout, or convenience to 10 fwd or whatever. Maybe if Beverly's quarters are closer to sickbay and she's really exhausted that week Picard stays there so she doesn't have to travel a few decks to his quarters. Or if one of them is on call because of a crisis they pick that way.
Everyone should do this. Marriages would last longer if people had their own living space and didn't have to bicker about who left too many lights on and whose turn it is to put out the rubbish. Unfortunately economics makes this a dumb choice for our century but since they did away with all that nonsense in the future there's absolutely no reason for people not to maintain their own living quarters.