Resmungona.
EN — Literal: "The (female) constant complainer"
EN — Meaning: A woman or girl who grumbles about everything and is never satisfied. The male equivalent is "refilão." Always moaning, always finding fault.
EN — Closest idiom: "Grumbler" / "Whiner" / "Moaner"
ES — Literal: "La refunfuñona"
ES — Significado: Mujer que se queja constantemente de todo, gruñona que nunca está satisfecha.
ES — Equivalente: "Gruñona" / "Quejica"