Meet The Phantom
The best way to actually understand Elly is through her children. She has April's insecurities, Liz's refusal to like social norms that get in her way and Mike's tendency towards rash and self-destructive behavior. She shares a further thing with all three of them: a blindness to the amazingly obvious. An example of that is when Liz made a habit of not realizing that the reason that Thérèse kept showing up at gatherings she was invited to was that Gordon wanted to remind The Evil Career Woman that if God had wanted her marriage to last, He would not have created Gordon Mayes.
The reason that I mention this is that just as I think that Elly has spent the day fifty five years of her life getting back at a woman who barely knew her back in the day because she allegedly stole a boy who Elly never stood a chance with, I join everyone left standing in her cohort in wondering why she never gave a boy who was and is crazy for her the time of day. It seems to them that he might as well have been invisible due to her habit of saying that she knew better than to assume that he carried a torch for her.