my sister wants recommendations for romance anime, she mainly does dub, she has done sub before but prefers dub. I usually am the one to recommend to her, but the main issue is that I have transfered to mainly manga about 2 years ago mostly out of convenience. Since I read the manga, it is hard to tell if the anime did the story justice without watching it personally. some romance animes she has enjoyed are:

snow white with red hair

fruits basket(2001) and current(she is waiting for the new season)

maid-sama

clannad

dance with devil's

your lie in april

vampire knight

this should help give you a baseline of the type she likes. I look forward to your suggestions.

P.S. she likes most things with a mafia theme or dominant/protective male leads