fall by the wayside
Fail to continue, drop out, as in At first she did well on the tour, but with all the pressure she soon fell by the wayside. This phrase appeared in William Tyndale's translation of the New Testament (1526; Luke 8:5).
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.