Under good or bad circumstances, with good or bad effect. For example, For better or for worse he trusts everyone. This term became widely familiar because it appears in the marriage service of the Book of Common Prayer (1549): “With this ring I thee wed, for richer or poorer, in sickness and in health, for better or worse, til death do us part.” [Late 1300s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
How to use for better or for worse in a sentence
We husbands, we lads of the for-better-or-for-worse brigade, we learn to pierce the mask.Indiscretions of Archie | P. G. Wodehouse