Andrea Westlund in her piece "The Reunion of Marriage" (in the Monist's Marriage issue) gives an account of the "companion love" in marriage as centered on the argumentative forging of shared reasons.
While there is some argumentative forging of shared reasons in marriage, it seems to me that any account of marriage that makes the production of shared reasons be central is a conceit of affluent Western culture (bet you never expected that phrase from me!). I imagine two peasants. They fall in love, marry, pray together, raise children together, work the fields with the children, are taken care of in their old age by some of the children, and go to their eternal reward (not all necessarily in this order—in particular, falling in love may follow marrying, and the praying together hopefully happens all through the process).
The couple's joint life follows a pattern set by religious and secular tradition, the cycles of nature, and economic necessities. In the ideal case, they do indeed share ends—they jointly pursue food, drink, shelter, clothing, eternal salvation, reproduction and various joys, all for and with one another and their children. Many of their shared reasons are a function of what they individually have antecedent reason to pursue (e.g., clothing and eternal salvation) and which become a joint end when they come together in love. But in those cases there is no need for a production of reasons—they have the shared reasons in virtue of their shared humanity and their shared circumstances, as well as, perhaps, their love. (I am suspicious of the idea of love giving rather than recognizing much in the way of reasons. One could try to argue that love takes individual reasons and transforms them into joint ones.)
There is, of course, a dialogical struggle to recognize the reasons they already have—they are not perfect phronimoi who automatically are cognizant of all the reasons present for them. And there will likely be much argument over means, but that is not what Westlund is talking about.
Still there will be aspects of their relationship where they do have significant freedom. On long winter evenings, do they play dice, tell stories and jokes, sing, dance, sew and/or carve? Which non-required religious devotions do they embrace as a family? Which of their needy neighbors will they support and in what way? But in the case of devotion and charitable activity, this is merely the working out of a shared plan for particularizing and pursuing imperfect duties which they have, independently of any forging of theirs, a reason to fulfill. If the couple is lucky enough not to be too exhausted from the day's work, there may be some time for evening recreational activities, and there there will be a need to choose shared ends—but that simply does not seem to be of the essence to the marriage. It would be unfortunate if the couple were unable to do this, but their companion love does not depend on the availability of this.
Tevye: ... But do you love me?
Golde: Do I love you?
For twenty-five years, I've washed your clothes,
Cooked your meals, cleaned your house,
Given you children, milked the cow.
After twenty-five years, why talk about love right now?
Tevye: Do you love me?
Golde: I'm your wife!
Tevye: I know. But do you love me?
Golde: Do I love him?
For twenty-five years, I've lived with him,
Fought with him, starved with him.
For twenty-five years, my bed is his.
If that's not love, what is? (The Fiddler on the Roof)