Taylor Swift seems like a really nice girl, and I'm not just saying that because she came to my school once. (My favorite part of that article is the guy who tried to give her his phone number.) She's probably my favorite hard-core rapper.
And yet it seems like one of the draws to date Taylor Swift is to have a break-up song written about you. And with how quickly the break-up comes, she basically has to be working on the song for the whole relationship. Your first date is dinner and a movie, and while you're in line at the box office, she's trying out couplets that rhyme "pain" with "again."
Maybe the songwriting starts even sooner than that. She might decide whose date offers to accept based on who has the catchier name for a song title. You can get a lot more mileage out of the title "Dear John" than the title "Dear FitzHubert." (And maybe this is the explanation I was looking for!)