>>37520268I would inform her, plainly and bluntly, that she is living a lie. Ash Ketchum is not now, nor will he ever be, interested in pursuing a relationship with her, and in all likelihood he forgot she existed the moment they parted away.
At the end of the day, OP, Serena existed solely to orbit Ash's disinterested dick. She retconned the main character's past to force a half-baked, completely one-sided love subplot akin to a fanfiction original character. She had no personality. She had no character development or growth. She was a retread of May and Dawn. Her "dream" was clearly thought up at the last minute to try and give her some semblance of depth (it didn't work - see previous point.) Her performances were as uninspired as she was and consisted solely of spinning and twirling. She could have been removed from the XY series, and next to nothing would be different.
She will never be brought up again. Nothing that happened with her will be brought up again. Nothing she did will ever be relevant. She is a complete failure by every possible metric.
The anime moved on; I advise you to do the same.