On the surface, the excellent Swedish film A Rational Solution is about a marriage that enters a major storm. Before the storm, the state of the marriage was exceptionally calm, functional, and satisfied. The marriage still had some sex in it, but there was no desire or passion in that sex. The sex had become as routine, predictable, and functional as the other marital activities and obligations—work, shopping, the preparation of meals, the eating of meals, the visiting of friends, and so on. The sex was only there as part (and not the ground) of the marriage.
The marriage was also much admired by the town, which saw it as a kind of lighthouse, a guide to the land of security and middle-class satisfaction. A marriage is an institution you enter by way of sex, but once inside, and once used to its rhythms, the institution takes on a life of its own and can persist without the perturbations of Eros. The surface of A Rational Solution is about the trouble that sexual frenzy brings to a stable marriage. The normal institutionalized sex is rudely displaced by actually good sex (wild sex, the sex of animals, the sex of life) that hits the marriage like something that fell from the sky. The husband connects with another married woman. Their connection is red-hot and cannot be cooled or removed. The two are consumed by flesh, kissing, fucking.
That is the surface of the film. The depth of the film is found in the paper factory that’s at the center of the community. The entire town depends on the factory—which processes destroyed trees into paper products—and yet not an ounce of tension exists between its workers and managers, between labor and capital, between the appropriated and the appropriators. The factory is an island of peace. Unlike the marriages in the community, the shop floor is somehow free of contradictions, conflicts, and disruptions. This peace, this serenity, haunts the film. In one scene, married couples swim in a lake at dusk as the factory looms in the distance. The couples are on the verge of a crisis; the factory, however, is completely at ease. Indeed, the only disruption that happens in the factory is directly related to the marriage troubles in town. What kind of factory is this? A factory that has no internal problems? A factory that keeps all contradictions and trouble outside of its gates? 
Your zeroing in on the factory as a place of calm caught my attention, primarily because Sweden (indeed, Scandinavia in general) is known to have fairly strong economic justice policies. As you doubtless know, the haves and the have-nots are not as distant as in the US, and labor is a respected and formally incorporated part of the process by which laws are made.
The impact, then, of this sort of ‘class truce’ on the marital and sexual relations of the Swedes may be a key part of this film—or, at the very least, of your interpretation of it as a person living in the US, where the social tension is distributed most differently.