Seems to me like her continuing to be interested in him after discovering what he's really like would make for more interesting reading. I think that you've really got three options here, rather than just the two. A character being enamoured of a celebrity only to discover that the celeb's public persona differs from their actual persona has been so widely done as to make it almost seem tropeish. A character discovering that the celeb is a douche but continuing to pine for him with no explanation would mean that you're writing a 1950s movie relationship, but at least it's not widely done today. Having her remain interested in him, but for different reasons than why she was originally enamoured of him, presents the most possibility for psychological wrangling and would make for the most interesting reading, I would think. JMO.