Who says that persons who are not known to each other, who have met only by chance are strangers. Two persons living in the same space within the walls of house can even be more stranger to one another. Not only that, the strangeness can develop after the intimacy. The persons can drift apart slowly and slowly without even realizing till it becomes a point of no return. They sit near each other physically but immure themselves in the impenetrable shells. They think their own thoughts which never leak and mix with one another. There is a complete distrust between them. Every word said by one is interpreted by another as adverse comment and there ensues a war which further alienates them.
Why even then under such suffocating conditions they live together sharing the same space. There are many factors. One of them is economic dependence of one of them on the other. Sexual urge is another because it is difficult to find it outside without for the fear of social stigma and humiliation. Another most important factor is the children which are like threads of silk, almost impossible to cut.
So, they continue to live physically together. For the outside world they are together though they are emotionally miles apart. Like the two shores of the river, they will also never connect directly to each other. Their lives will run unhappily parallel to each other. Unhappy in their own ways.