一日三秋的英文：
[Literal Meaning]
one/day/three/season
A day absent from you is like three seasons.

[解释]
三秋：三年。一天不见面，就像过了三年。分别时间虽短，却觉得很长。形容情侣非常思念。

[Explanation]
(of lovers) long time no see

[例子]
李明出国后非常想念新婚的妻子，有一日三秋的感觉。

[Example]
When abroad, Li Ming missed his newly-wedded wife very much and felt one day away from her seemed like three years.

[英文等价词]
days creep by like years