On Swift's last album 1989, many songs are believed to have been about her relationship with Styles, most notably "Style" and "Out of the Woods." Styles was also allegedly the inspiration for "I Knew You Were Trouble" off her Red album.
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"Perfect," which was written by a team that included Styles and bandmate Louis Tomlinson, seems to be a direct response to those Swift songs. Here's a rundown of the most crucial evidence: