同士の

between … themselves

→ 同士
phrase Rare #20,590
between … themselves Follows a noun to describe a relationship, interaction, or event between people or things of the same type.
JA: 友達同士の会話は気楽だ。
EN: Conversations between friends are relaxed.

奥さんの帰りがいつも遅くなるでしょ頼むのは恐縮で隣人同士のよしみよ

Your wife always gets home late, right? I hate to ask, but as neighbors…

— 花様年華 (2000)

コルシカ人同士の殺し合いがあるから

Because Corsicans are killing one another.

— 預言者 (2009)

兄弟同士の殺し合いは許さん

I won't tolerate brothers killing each other.

— マルコムX (1992)

正反対のもの同士の友情

A friendship between polar opposites

— RRR (2022)

なんで、男同士のカップルなんだ?

Why are they a gay couple?

— ベイビー・ブローカー (2022)

男同士の秘密だ

It’s a secret between guys.

— ドライヴ (2011)

車同士の正面衝突でした。

It was a head-on collision between two cars.