To be honest, as unsmooth as the romances in HP were, I don't think they can be used as evidence that she sucks at romance. She was (largely) writing about teens, and teen relationships are always messy. and further than that she was writing, not primarily for an audience of children and teens, but definitely had to write all that in a way that would be okay for them (and there absolutely is a set of widely-accepted guidelines on this in the publishing industry), so she couldn't exactly...~make it real, if ya know what I mean.

I haven't read any of her other work but I understand they were for an adult audience, so I kinda have to try them to see how she can do romance without any blocks.