For millions of years in the history of human evolution, people stayed in groups or tribes. At that time when productivity was very low, human beings are too weak to fight against nature or other disaster alone, so they need the help and protection from others to survive. But now things have changed greatly, men and women prefer living alone. In some developed countries men seldom get married before 35 years old. Nearly 50% marriages end in divorces. More women are independent economically. They even get pregnent by buying sperms from genetic banks and raise their kids alone.
What's the reason of this phenomenon? Is it wealth caused by economy development? or the security provided by modern country's welfare? An obvious reason is that the people can live independently as well as comfortably. Economy is not the only reason. There are also some other social culture and psychologic reasons.
To live alone doesn't mean to live lonely. In fact there is few evidence which can prove that. Research finds that lonely feeling doesn't come from living alone. If you married the wrong person, you may feel more lonely with him/her than your living alone. Theoretically living alone causes less communications between people.