琴瘦放开那姑娘

The stringed instrument becomes thin and should release the lady. If 'qin'(琴-a stringed instrument similar to western lute) stands for players, it indicates a male player gives up playing for letting that lady away. But generally, it sounds poetic in expression but a little obscure in real implications unless users offer us more contexts or hints about the source. A possible explanation is a man stops playing instruments, releasing someone, and possibly referring that the music ends, implying parting. Besides that, 琴 (Qin) in Chinese literature is also associated with scholars and elegance, sometimes melancholy and solitude; the sentence may mean giving someone freedom despite having deep ties or attachments.