It’s always the little things that help light the fuse - maybe someone cut her off. Her hair keeps falling in her eyes. Something triggers the enormous anger that has been building up since she was first called worthless back in second grade and suddenly she’s Michael Douglas in Falling Down, taking hostages, crashing cars and finally, in a culmination of years of bad advice, failed attempts and broken relationships, she strikes the match.
She watches the match burn down, then blows it out before she touches it to the fuse.
No telling what will happen next time.