It is worth pointing out that those who cannot afford rent often will not subsidize their situation by renting out extra space and taking on roommates, but instead suffer in isolation living alone. This false premise that "living alone" is some sort of social achievement needs to end.
Is there any evidence that more people are attempting to live alone now than in the past (in the US)? Genuine question -- don't know the trend national trend.
Mean is a bit of a misleading number here since the distribution really is discrete - and there are a lot more 1 and 2 person homes today than before, which is contributing to the lower average.