This quote suggests that marriage is a transition from a series of short-lived, foolish behaviors or decisions to a long, continuous one. According to Nietzsche, the “short follies” might refer to the various mistakes, misadventures, or relationships one may have before settling down. They are “short” because they are temporary, fleeting, and often experimental. However, Nietzsche labels marriage as “one long stupidity”, implying that it is a prolonged, unchanging state of being that may be as foolish as the short-lived follies, but lasts for a much longer period.

The term “stupidity” used here doesn’t necessarily mean that marriage is unintelligent or unwise. Instead, it might suggest that marriage, like the short follies, involves its own set of mistakes, trials, and tribulations that are continuous and enduring, rather than temporary. However, unlike the short follies, these challenges are faced with a single person over a long period, making them appear as one long, continuous folly.

In today’s context, this quote might be interpreted as a critique of the societal pressure to get married or the romanticization of marriage. It suggests that marriage, like any other aspect of life, is not free from its own set of challenges and follies. It might also be seen as a reminder to not view marriage as an end-goal or a solution to one’s problems, but rather as a different stage of life with its own set of challenges.

In terms of personal development, this quote could serve as a reminder to approach marriage with a realistic mindset. It suggests that one should not expect marriage to be a perfect state of being, but rather a journey filled with its own set of ups and downs. It could also encourage individuals to learn and grow from their short follies before entering into the long-term commitment of marriage.