I think people focus way too much on romantic relationships. And many seem to see them as their lazy ticket out of loneliness.
If you want to improve social skills and alleviate loneliness people have to start and grow healthy communities, friendships and family bonds.
Capitalist thinking has reached interpersonal relationships. Instead of seeking community, people focus on how to optimise their dating market strategies and such. That's pretty fucked up.
I think that's also the reason why people lack interpersonal bonds. Investing into communities, friendships, relationships doesn't fit into a world that is focused on linear progress and material gain. Applying this type of thinking (success, optimization, comparison, ...) seems to lead mostly to resentment.
But community is not something you can teach, I think. You can facilitate it by providing opportunities for community building. Like the so called third place and enough time for people to get together casually.
Ultimately it's something we inherit from generations before, though. And we only stray ever further from it. It's in our hands now to do it in our lifes, online and in our neighborhoods etc.