The screenwriter had just finished shooting 1999 movie Dogma with the singer when they went for a late-night stroll along a Los Angeles lane.
But when a threatening man approached, Smith got set to run away and leave the Ironic hitmaker to fend for herself.
In his new book, Shooting the S**t with Kevin Smith, the Clerks director writes, "While I didn't immediately push Alanis into the dude and run away, I separated myself from her. The chivalrous thing would have been me putting myself between her and harm's way, but I thought, 'She's a tough broad. I'm running and hoping that she's smart enough to run too.
"I could tell that if I had had any shot of getting together with (her), it went out the window that day."