You see these articles going around ever so often which seek to advise people on how to achieve a happy marriage by explaining who marriage is "for". It's not for you. It's for your spouse. Seek to make your spouse happy, and all will be well. Or perhaps it's not for either of you but for children. If you both seek to form a good family for their sake, it will all work out. I suppose it's only a matter of time until someone writes that it's actually for society -- though perhaps not as that is not exactly the spirit of the day.
Aside from often coming off rather saccharine, the problem with these attempts is that they seek to find the measure of good (in this case, good in the context of marriage) in another person.
Obviously, in a marriage, your spouse is a key element. You two will be responsible for making each other happy or unhappy, united or divided. And the particular feelings and preferences of your individual spouse are important as far as the details of how a loving marriage is expressed. One woman may be made to feel most happy by surprise gifts of flowers and offers to watch the kids while she goes off to have some time away with "the girls", while another cares little about gifts and flowers and girl time, but very much cares about her husband being home to spend time with her as much as possible. One woman very much wants her husband to take her out somewhere she can wear a nice dress and heels and that lipstick that she bought last week, and another really hates it when she feels that she's being forced to dress up. One could identify the same variety of desires among men. In these little details, there is necessarily a great deal of variation because there are many sorts of people and one clearly ought to make the effort to learn what one's spouse wants and meet those desires and not some other arbitrarily chosen set.
However, while the way one may work out one's love toward one's spouse will vary a great deal from marriage to marriage based on the desires and circumstances of each couple, what makes a good marriage is not simply "making it about the other person" or "doing what your spouse wants". If doing good within a marriage simply meant doing what your spouse wanted, then that would lead us to the contradictory idea that if you spouse wanted something that was bad, it would be good to do bad. For instance, in the formulation that marriage is "for" making your spouse happy, if your spouse was in fact deeply selfish and could only be made happy by you acting in a way that was destructive to you, the "marriage is about making your spouse happy" dictum would suggest you should go ahead and behave self destructively in hopes of making your spouse happy. In fact, if we take moral law at all seriously, such a course of action would not only damage you, it would damage your spouse as well, since being the cause of wrong action is itself damaging.
Marriage is for virtue, not for your spouse or for the kids or for society. Virtue entails, among other things, working for the happiness of your spouse, to the extent that that happiness is ordered towards good things. But it is virtue which is the defining element, not simply the desires of your spouse. There can only be one source of Good, and that can never be another of us imperfect human beings.