lose the thread
Cease to follow the sense of what is said. For example, It was such a long story that I soon lost the thread. This expression uses thread in the sense of “something that connects the various points of a narrative.” [Mid-1900s]
Words nearby lose the thread
lose one's touch,
lose oneself in,
lose out,
lose sight of,
lose sleep over,
lose the thread,
lose time,
lose touch,
lose track,
losel,
loser