But he felt no delight. Therefore a man who is lonely feels no delight. He wished for a second. He was so large as man and wife together. He then made this his Self to fall in two (pat), and thence arose husband (pati) and wife (patni). Therefore Yagnavalkya said: 'We two are thus (each of us) like half a shell.' Therefore the void which was there, is filled by the wife. He embraced her, and men were born.

In plain words: He still felt no joy, which is why a lonely person feels no joy. He wanted a companion, so he split himself in two, and husband and wife came into being. The sage Yajnavalkya said a married couple are like the two halves of one shell, and a wife or husband fills the empty half. From their union, people were born.