I see this phenomenon of choosing to be alone as partly politically partly culturally influenced.
Contemporary human society, at least the Western world is moving towards values more oriented to individuals and their rights. Individual freedom is among the highest values in western societies and western influences are quickly affecting the East as well. On one hand, this seems to be influenced by capitalism and the right-wing politics with which the idea that everything must be private is pushed along. But on the other hand, left-wing politics influence this even more by emphasizing individual rights of the minorities and/or social groups who were long suppressed and experienced social inequality - this affects whole other, and more important - cultural and artistic field, through which ideas settle in human psyche more quickly and easily. Nobody likes to be repressed, everyone wants freedom, and compassion is quickly felt towards whoever fights for their freedom. So this is kind of a meeting point of the left and right - individual freedom, just approached from different perspectives and thus this value is highlighted through various means in contemporary culture. And when this value is highlighted in surrounding culture it's much easier to highlight it in your personal system of values and start considering things from there.
In the past, even in the West, traditional values (that are almost a synonym for collectivism) were more highlighted. Christian values, or generally values of organized and strictly structured religions that have little room for individualism were more widespread. Now many more people are atheists, so-called free believers, spiritual but not religious, etc. Nationalism was more widespread in the past, now globalization and interconnectedness are prevailing and this makes people focus less on confined units such as nation or even family. This staying alone phenomenon could be seen as a balancing force to historical emphasis on traditional communal values. Maybe it's already gone a bit too far the other direction, but in that case, balance will be brought again sooner or later.