We are basically committed to each other for sex but it's very hard to make those relationships last a long time because we might not have anything in common, we might not share anything with each other, we might not trust each other, we are not particularly bonded to each other.

我们基本上只有激情的承诺,长时间维持这种关系很困难,因为可能双方没有任何共同点，没有共享的东西，我们可能互不信任，不是特别亲近。

耶鲁公开课 - 心理学导论课程节选