Correct

一日不见,如隔三秋

/ yī rì bú jiàn rú gé sān qiū / 
Strokes
https://i.cchatty2.com/filters:format(webp)/fit-in/684x0/img/202102/一日不见如隔三秋-Chinese-idioms-Cchatty-447fd44e-fa82-45b3-9db2-dd84163c08f5-1612776098.jpg

Collocation

1
感到一日不见,如隔三秋啊
2
真是一日不见,如隔三秋
3
有一日不见,如隔三秋的体验

Definition

一日不见,如隔三秋:

Literally means:

a day's separation seems as long as three autumns

Actually means:

三秋, three autumns, refers to three years.

It means missing very much. It also refers to very slow progress.

三秋,三年。

一日不见,如隔三秋,一天不见面,就好像隔了三年没有见面一样。形容特别思念。也形容进展缓慢。

Example

Used as a minor sentence, or as attributive or object. (作小句、定语、宾语)
1
Lǎogē
老哥
  
,
yīrìbùjiàn
一日不见
  
,
rúgésānqiū
如隔三秋
  
,
zhēn
真
xiǎng
想
nǐ
你
ya
呀
  
!
Shēntǐ
身体
hǎo
好
ma
吗
  
?

Brother, don't see you all day, such as every three autumns, really miss you! How's your health?

2
Chǔyú
处于
rèliàn
热恋
zhōng
中
de
的
qíngrén
情人
  
,
yībān
一般
dū
都
huì
会
yǒu
有
yīrìbùjiàn
一日不见
  
,
rúgésānqiū
如隔三秋
de
的
tǐyàn
体验
  
。

Lovers in love, generally will not see one day, such as the experience of three autumns.

3
Zhèlǐ
这里
bú
不
shi
是
méiyǒu
没有
jìnbù
进步
  
,
érshì
而是
jìnbù
进步
tài
太
màn
慢
le
了
  
,
ràng
让
xìngjí
性急
de
的
rén
人
juéde
觉得
yīrìbùjiàn
一日不见
  
,
rúgésānqiū
如隔三秋
  
。

Here is not no progress, but progress is too slow, so that anxious people feel that the day does not see, such as every three autumns.