Final answer:
A couple marries to legally form a social union, often involving the agreement to make household and child-rearing decisions together, with potential variations in financial management and head of household roles. The importance and assumptions about marriage are evolving, influencing societal norms and laws.
Step-by-step explanation:
When a couple marries, they make a legally binding agreement to form a socially recognized union, and depending on the society, this union may be between individuals of the same or different genders, and can include various arrangements for living, child-rearing, and economic support. This union often involves agreements to make household and child-rearing decisions together, though the handling of finances and the designation of a head of household can vary greatly between couples and cultures. Marriage traditionally involves a partnership that is geared towards establishing a stable socioeconomic household, with shared responsibilities and labor contribution.
However, it's important to note that the assumptions about marriage and family are evolving. Increases in cohabitation, single parenthood, and same-sex partnerships are altering the traditional notions of marriage, and as a result, the tax laws, banking, and loan processes that favor marriage might be reassessed. Nonetheless, marriage continues to be an arrangement that provides a structure for raising offspring, reducing competition for mating partners, and creating alliances that cross familial and social networks, though its many functions can vary greatly