One reason people enjoy marriage is the same reason pets enjoy living with humans. We grow addicted to the physical proximity, affection, and regular meals. These are the most animal parts of marriage, and the easiest to get right. The mental, emotional, spiritual parts are harder to lock down.
Lao Tse talks about emptying yourself. Buddha talks about nirvana and non-self. St. Paul calls us empty clay vessels. Hinduism teaches us about the true self, underneath and behind the delusion. Jesus tells us of a possible second birth. These are the same. When they appear, they are named differently. This sameness is the mystery. Mystery within mystery, the door to all marvels.