This happens all the time. In the recent Netflix show 13 Reasons Why, the main character starts with long hair. Later she cuts it, then kills herself. We would have included a spoiler alert, but she's a girl in an article about girls in TV shows getting haircuts, so you already knew what would happen.
Sometimes the resetting-your-life-with-a-haircut trope is played for laughs. In Mean Girls, we learn that after Regina George made fun of Janis for being a lesbian, Janis dropped out and "all her hair was cut off, and she was totally weird." But most times, these haircuts are very, very serious. In the movie Joy, Jennifer Lawrence gets swindled out of all her money. Explaining how that affected her character could be done with a scene of her at her bank, followed by a montage of her scowling over bills and repo men. Or you can do what they did:
20th Century Fox