I keep coming back to what @likeadevils said about how Taylor kept coming back to her fear of getting older in writing Red but kept cutting it from the album.
The Taylor who wrote Red was coming off back to back relationships with older men where her age was a reason they pursued her AND a reason they ended things. She was also trying to continue a career where her accolades were made to seem more significant because they often came attached to a “youngest ever” label.
This era saw Taylor publicly embrace a more mature persona - abandoning the fairytales and whimsy that were once staples of her brand. And yet privately she wrote about how terrifying getting older was. She was desperate to grow up and stay young at the same time because of the way the men in her life, and the industry feel about age.
Imagine the mindfuck of knowing your naivety and youth are hot commodities to older men but your perceived childishness is the reason they’ll abandon you. Growing up would be a way to simultaneously protect yourself from and prove yourself to these men.
Imagine seeing how hard the women in the industry work to cling to the appearance of youth. How women she grew up admiring fell off the charts as soon as either their 20s or their beauty left them. Conversely starting her career as a teenager and writing about high school and first loves was where her detractors drew from for critique. She wasn’t a real musician to them, she was a child star.
Ultimately the desire to grow up, to be perceived as a woman and a serious music heavyweight won out. Red was her transition out of girlhood made clear and at the time it seemed like she bridged this gap effortlessly, but in the vault and on the cutting room floor she left behind traces of the battle it took to get there and the fear of what she was leaving behind.