Understand that this phrase implies potential negative outcomes of ones' actions or decisions. He treads a fine line by arriving late so often; one more time and he might get fired.
Pro Tip 2/3
Implied Risk
Recognize that the situation involves a risk, which requires careful and balanced actions. She walks a fine line by investing heavily in an unstable market.
Pro Tip 3/3
Subtle Tension
The phrase can express a subtle tense situation where balance is critical. During the negotiations, he walked a fine line to keep both parties satisfied.