It means you either neglected her like everlyn101 said, or that you chose too many opposing things when it came to the girl's development. Each choice has an icon that shows which type it is, it's generally helpful to make choices that have the same icon to guide her down a path. For example, making a bunch of choices with the dampness icon during the recluse's section will likely have her turn into either a hairy mycena or a ink cap mushroom if she's relatively well cared for.