Awww dizzy, I'm sorry your gf felt that way. Its tough sometimes. Tell her not to be upset, not all fashion trends that come out suit all body types. There is definitely a jean out there that probably she can rock better than any girl next door.

If she has shorter legs and she doesnt want to wear heels, the next best trick is to get dark denims. They create the illusion of length. Boot cut jeans are best, they flatter every shape and will always be in fashion. (hopefully the men in Diesel dont hear this comment... ) Tell her to make sure the hem is only 1cm above if not just grazing the floor.