If you don't have any plans to marry her, I think you should consider breaking up.
ご質問ありがとうございます。
・「If you don't have any plans to marry her, I think you should consider breaking up.」
（意味)彼女と[結婚](https://eikaiwa.dmm.com/uknow/questions/36367/)する気がなかったら別れたらいいのに
<例文>If you don't have any plans to marry her, I think you should consider breaking up. I believe it's for the better.
<訳>彼女と結婚する気がなかったら別れたらいいのに。 そっちのほうがいいよ。
参考になれば幸いです。
If he doesn't want to get married to her, maybe they should go their separate ways.
この場合、次のような言い方ができますよ。
ーIf he doesn't want to get married to her, maybe they should go their separate ways.
「彼は彼女と結婚したくないなら、別れたらいいのに」
to get married to ... で「…と結婚する」
to go one's separate ways で「別の方向へ行く」＝「別れる」
ご参考まで！
アメリカ合衆国 
カナダ 
