WCIF this lost dress? It's called Gothic Lolita V5 Costume by Cosplaysimmer. Thing is, all of Cosplaysimmer's stuff got deleted for some reason. Paysites.mustbedestroyed.org does not have it. : r/thesimscc
The Sims Resource - Lolita Dress
My Sims 4 Blog: Classic Lolita Mini Dress for Males & Females by Sims 4 Marigold
Lolita Fashion Store in The Sims 4 (using CC, links included) - YouTube