It doesn't matter what the narrative logic demands. For women, the fairy tale demands that the cute guy gets the girl, not the loser gamma:
Howard Deutch and John Hughes thought they had "Pretty in Pink" all tied up at one point. The director and writer/producer, respectively, shot the ending, finished the final edit and rolled out a version for feedback.

Much to their surprise, audiences actually really disliked the film's ending, to put it mildly.

“The ending didn’t work in the test screening … That shocked everyone because the architecture of the story was that love endures and overcomes everything,” Deutch told The Huffington Post about the original ending, where Phil "Duckie" Dale (Jon Cryer) and Andie Walsh (Molly Ringwald) end up together.

“The girls in the test screening didn’t go for that. They didn’t care about the politics; they wanted her to get the cute boy. And that was it. So we had to reshoot the ending," Deutch said.
Forget love. Girls want cute. The mistake that Hughes made - to the extent it can be called a mistake given how successful the movie was - is that if Duckie was going to get Andie, he needed to up his socio-sexual status.