The noses should point in the same direction
As I wrote last week, one person lasts longer than the other, such as the Belgian couple (blog 2) whose husband lasted longer than his wife. In practice, it is difficult to maintain an alcohol stop within a marriage or relationship if the other person gives up quickly or does not want to start at all.
Imagine that you are at a party and your partner drinks the necessary drinks. You can skip a discussion about who should drive home, because that's a foregone conclusion. Eventually you can persuade your partner to go home at the end of the evening, of course after the necessary 'one more because he/she has such an insanely good conversation with someone'. By the time of 'really the very last' you've already been quite annoyed how your partner behaves ridiculously in your sober eyes. It could just be that you explode on the ride home and a fight ensues because your partner is talking pretty stupid or repetitive from your sober perspective. When you get home, your partner calls out reproachfully: "Nowadays you don't have any business anymore", so you have to be very strong in your shoes not to take that offered nightcap and to go to bed obediently and then spend an hour or two lying awake in frustration until Mr./Madam comes to lie next to you with a considerable alcohol fume and falls asleep like a log. Your reward isn't until the next morning, but then again...
Incidentally, there is no guarantee at all that if both partners drink the necessary alcohol, there will never be a fight. On the contrary, alcohol makes loose lips, old cows are soon taken out of the ditch or precarious matters such as money, raising children and family (visits) are under discussion and before you know there is thunder in the tent and often even worse, because we all have heard of domestic violence.
In short, it would be ideal if cohabiting partners both put their shoulders to the challenge, so that it is easier to keep up. If one lasts less time than the other, it is important that the 'persistent' continues to be stimulated by his partner.
Well, that's a nice theory, but how difficult is everyday life if your partner drinks his glass every day and you watch with a slanted eye?