It's fascinating to me that Nietzsche had cogent things to say about an institution like marriage, given that he never wed. But so it is. Here is a quote on the topic from Human, All Too Human (Volume I, § 406):
Marriage as a long conversation. -- When entering into a marriage, one ought to ask oneself: do you believe you are going to enjoy talking with this woman into your old age? Everything else in marriage is transitory, but most of the time you are together will be devoted to conversation.
Naturally Nietzsche thought he was writing only for men (was that really only 120 years ago?), but otherwise I find his comments insightful.
Peter Saint-Andre > Journal