In some countries, more people choose to live by themselves in recent years, why is it case? Is it a positive or negative development for society?

Living alone has become increasingly common in many countries as social norms, housing markets, work patterns, and personal expectations change. This trend is driven mainly by greater individual autonomy, later marriage, mobility, and longer life expectancy, and I believe it is mixed but potentially positive if societies prevent isolation and make single-person living sustainable.