the grass is always greener on the other side 的字面意思是“另一边的草看着总是要绿一些”。这个表达在中文里相对应的意思是“邻家芳草绿，隔岸风景好；这山望着那山高”。

【例句】
You don’t know that for sure. The grass is always greener on the other side.
你又没有百分之百的把握。人总是这山望着那山高。

Julie is always moaning about how small her house is compared to mine. It really isn’t. But I suppose the grass is always greener on the other side of the fence.
朱丽总是抱怨她的房子比我的小，其实根本不是这样。不过也难怪，人们总是觉得别人的条件比自己的好。