Consider the question. Has Justin Timberlake ever written a song about Britney Spears?
 What is the step-by-step reasoning process to arrive at the answer: yes?
Justin Timberlake and Britney Spears dated in 1999. In 2002, Justin Timberlake released a music video for his breakup song 'Cry Me A River' and featured an actress who resembled his then ex Britney Spears.