Why is loneliness more common? Look at the work week. Everyone is working long hours, doesn't get time off, or is too broke to spend it doing social stuff in America or other countries. Lots of fear increases this too, with people working too much social skills go down and mental health issues become an issue. And lack of interactions with others increases fear in general.

Now if you are lucky enough to be well off enough not to have that issue then the second thing is tech replaces people in a lot of areas - food, entertainment, health, ways we connect with others etc. If you had to rely on others more I bet most people would be less lonely in general. Isolation becomes easier the more tech you have available - be it cars or computers it can easily isolate you if you don't purposely avoid isolation. Now tech can bring people together, I'm in a long distance relationship and tech makes it very easy nowadays but it's still not the same, as in person face to face experiences.

But I also think people will always face loneliness in every generation, it just might go by other names.