Most people’s marriages just muddle along, because marriage is “against human nature”—people get bored of what’s familiar and crave novelty, but circumstances don’t always allow otherwise.

Marriage doesn’t necessarily bring happiness; it’s a cornerstone of social stability: it gives people something to keep in mind, so they’d rather keep going as “beasts of burden.”
Once the novelty fades, that’s when a marriage can truly be considered truly fulfilling. From then on, what they rely on is conscience—mutual endurance, compromise, and exhaustion; a process that can be called “practice.”