Psychology professor Laurence Steinberg looks into delayed adulthood and comes across marriage:
For many, after its initial novelty has worn off, marriage fosters a lifestyle that is more routine and predictable than being single does. Husbands and wives both report a sharp drop in marital satisfaction during the first few years after their wedding, in part because life becomes repetitive. A longer period of dating, with all the unpredictability and change that come with a cast of new partners, may be better for your brain than marriage.