Their love was built on the sand,that is why their marriage has landed on the rocks.
他們的愛情缺乏堅實的基礎(chǔ),這就是他們的婚姻瀕臨破裂的原因所在。
built on the sand 字面意思是“把......建筑在沙土地上”,喻指“基礎(chǔ)不牢固”或“不切實際”,常用于口語之中。
比如:
I hear he decided to invest in a film,it is built on the sand.
我聽說他要投資拍電影,這太不切實際了。