Become One Flesh Meaning

(idiomatic, of two persons) To join together in marriage; to develop a unifying bond as a result of marrying.

Example: 1847, Charlotte Brontë, Jane Eyre, ch. 37:
  "We must become one flesh without any delay, Jane: there is but the licence to get—then we marry."
1997 June 30, "People: A Bit of a Fit Over Pitt Split," Time:
  Just when it seemed like BRAD PITT and GWYNETH PALTROW were moving so smoothly into becoming one flesh that they even had the same haircut, they abruptly called it all off.
2011 Feb. 11, Jennifer Schuessler, "Inside the List," New York Times (retrieved 2 Nov 2012):
  â€œWhen my husband and I got married, we became one flesh,” Drummond wrote in a recent post.