A relationship or connection between people — the nature or terms of their association (e.g., friendly, professional).
彼とは学生時代からの間柄だ。
He and I have been close since our student days.
上司と部下の間柄をわきまえるべきだ。
You should be mindful of the relationship between a boss and a subordinate.
親戚の間柄だから頼みやすい。
Because we're relatives, it's easy to ask a favor.