这样说并非完全没有缘由。

It is not altogether without reason to say so.

《新英汉大辞典》

我的不快乐没有缘由。

There was no reason for my unhappiness.

youdao

有时候有些事情就是这么发生了，没有缘由的发生并美好着。

Sometimes things just work and there is no further explanation than that.

youdao

More in number than the hairs of my head are those who hate me without cause.

恨我之人多如牛毛,没有任何缘由。

耶鲁公开课 - 旧约导论课程节选