I don’t know if I have a lot of insight into Elia. It’s interesting that in her case, her fate was decided by her mother and not her father, but she didn’t end up any better than Lysa or Cersei or Catelyn.
From the little we learn about her, she seems like a genuinely good person whose life was completely obliterated, in part by the schemes and callousness of men with power, and in part because the man she loved cared so little for her. Leaving aside Lyanna – why the hell did he not keep her in Dragonstone or send her to Dorne, where she would be safe? Why leave her in the custody of a lunatic who hates her?