She's too hung up about other people's appearance/looks.
She's a real stickler when it comes to other people's clothes and hair, make-up, etc.
ーShe's too hung up about other people's appearance/looks.
「彼女は相手の格好/見た目にこだわりすぎる」
be too hung up about ... で「…にこだわりすぎる」
appearance で「格好」
looks で「見た目」
ーShe's a real stickler when it comes to other people's clothes and hair, make-up, etc.
「彼女は相手の服や髪、メイクなどになると、かなりこだわる人だ」
stickler で「こだわる人」
when it comes to ... で「…にかけては・…となると」
ご参考まで！
カナダ 
