Yesterday it was 20 years ago I met my husband. That means I have known myself with him for longer than without. I think about that standing in a cafe window ( sitting is still not something I do if I don’t have to). I am an hour early for my appointment because I made a mistake with the time. I am usually just in time for things so an hour extra is a special gift. And thinking about time, 20 years, 15 of which we have been married, is a hell of a lot of hours. A good friend of the family commented that the second 20 years are actually much easier so we have many good hours to look forward to, if he is right.

Research consistently shows that married couples are happier than non-married couples, across cultures (Diener, 2002). Is that because marriage makes you happy? Or is it because if you are happier you are more prone to getting married? It is most probably neither. As a researcher you always need to be careful making conclusions that imply causal relationships. So just because married couples are happier you can’t say marriage will make you happy.

The reason for being careful with such conclusions is the odd confounder lurking behind your observed associations (see McNamee for a nice overview and update of the concept, 2003). A confounder is a factor that will affect both your outcome variable (happiness) and your proposed explanation (marriage), or exposure as epidemiologists prefer to term it. A confounder should also not be a variable mediating the effect of the exposure on the outcome (marriage causing something – a mediator – causing happiness). The only way to discover a confounder is to remember to think of it and measure it.

In the case of happiness and marriage an important confounder seems to be commitment. Couples are more prone to marry if they are more committed and the investments they have made in their relationship due to their commitment seem to make them happier. After all, you’d be silly not rewarding yourself with happiness for all the effort (Rusbult, 1998)! It also seems, not surprisingly, that perceived commitment on the partner’s side increases your own commitment (Joel, 2013). It is also pretty intuitive that commitment predicts forgiveness for betrayal (Finkel, 2002).

So commitment is what keeps a happy marriage going. For me it’s commitment to growth and to work things out. Because challenges occur in all marriages. Even if children are wonderful, marital quality declines in the majority of couples after childbirth (Doss, 2009). You just have to work out a new way of being a couple. Things like illness or losing a job can also take their toll. Today I am also reminded of my brother-in-law, Martin, who would have turned 36 if he hadn’t died suddenly at the age of 26, leaving a child and a pregnant wife behind. So we are lucky until we have time on our hands to work things out. With the first 20 down, I am certainly committed to more!