你说的情况在定语从句中常出现。situation ，case ，point作先行词时，关系词一般情况下用where。如：
I have reached a point in my life_where_I am supposed to make decisions of my own.
It's helpful to put children in a situation_where__they can see themselves differently.
其中有特殊情况的词是point，因为它既可以表示地点，又可以表示时间。如《牛津词典》上的例子：
We have reached the point 时刻；关头；阶段_when__we have no money left.
对比：
This is the point某地方；地点_at_which_the river divides。