What part of your relationship with your Japanese boyfriend/girlfriend is difficult?
What do you find challenging about going out with your Japanese boyfriend/girlfriend?
この場合、次のような聞き方ができますよ。
ーWhat part of your relationship with your Japanese boyfriend/girlfriend is difficult?
「日本人の彼氏/彼女との関係のどの部分が難しいですか？」
ーWhat do you find challenging about going out with your Japanese boyfriend/girlfriend?
「日本人の彼氏/彼女と付き合って何が困難に感じますか？」
ご参考まで！
カナダ 
