Did Princess Dia ever make any real friends?
 

A sub plot that was never settled or expanded was Princess Dia sad life that no one cared about her, people only cared about her title or her treassure. Why bring up that sub plot and not do anything with it? Was this to show how much better and luckier that Princess Serenty was in comparrison to her in that she had real friends that cared about her, and that is what she desired.

A kind of wish they did something with that, at least the first anime, the manga might not have had time for that, but the 90's anime had all the time in the world, though I think that sub plot is not in the original anime.

Re: Did Princess Dia ever make any real friends?
 

Sadly probably not. But we never saw enough of her to know for sure.