Light side Jaesa is still a Jedi, and the story line says she keeps in line with her Jedi path. Your failure to understand the Jedi Code (which forbids love/romance) is not BioWare's fault. I think preventing light-side Jaesa romance is better in keeping with the history and legitimacy of the Star Wars universe. The counter to this on the Republic side of the Jedi who have romance options are your player's choice to not follow the code.