What does 七年之痒 mean?
It means seven years after marriage, both husband and wife would face numerous temptations that would harm their relationship. The seven years is a vague expression, sometimes a couple gets trouble earlier, sometimes later.

There is a movie about this. Wikipedia has some hints too. Its Baidu page tells that it's borrowed from foreign country.



Case Study

There is a perfect case: 潘粵明 與 董潔, matching the definition pretty well.