> shows that loneliness is worse in each successive generation.
Basically if you read the linked to report, the data show older people are less lonely than younger people right now. That’s not the same as showing loneliness increasing over time. There are many plausible reasons for younger people to be lonelier... it’s just as likely younger groups are always lonely and lose loneliness as they age.
The rest of the article talks about partisanship, which is a different issue entirely. Indeed as we sort ourselves into ideologically similar communities I might expect loneliness to decrease.