I don't think the decline of the family is the primary issue today. My own perspective is that the "epidemic of loneliness" has more to do with the prevalance of, and addiction to, social media in its various forms.

It is easier than ever to form and maintain all your relationships, acquaintences, friends, and family, online via social media. You can see what people are up to, even "participate" to some degree via commentary/messaging, and it leaves people feeling like they've done their part in keeping the relationship alive. My observation is that because relationships kept this way are increasingly normalized, people are less interested in getting together in the physical world because it takes a lot more effort, and requires a much more significant investment in time.

On the plus side, it means you can keep relationships alive across great distances, and even during times where life is so busy that you have limited spare time.

But the problem is that forming meaningful relationships becomes an increasingly difficult task, to the point where you can begin to wonder if there is something wrong with you due to not being able to form those relationships. Further, you feel increasingly disconnected and isolated, when you have a lot of skin-deep relationships, but none which are truly meaningful.

I consider myself lucky to have a wonderful wife, and her company is more than enough to sustain me even when nobody else is around; but both of us still feel the isolation when we are unable to get together with friends for too long. We moved away from my home state, and she immigrated from another country, so both of us have left friendships behind, and been trying to form new relationships near where we live. It has been harder than expected, and I think it is in part due to people finding it really easy to blow off getting together in person when there is even the slightest inconvenience, especially knowing that they don't have to actually meet in person to keep the relationship alive.

As a result, my pet peeve these days is when people, when asked why they keep blowing off getting together, say "I've been so busy". For one, it is a meaningless statement, most people are busy, it is just the nature of having to work at least one full-time job and then fit in the other activities you want to do in the time left over. Most people still find time to get together with friends at least once in awhile. Thanks to the perpetual need to post everything on social media, it is usually evident that the "busy" person is not really actually busy, and instead what they really meant was "I've been too busy doing things I value more than our friendship, but am too uncomfortable to tell you that".

I don't know if it is related or not, but in my experience, the detachment derived from social media seems to go hand in hand with avoiding anything that is perceived as unpleasant, such as being honest with someone when it is a hard truth, e.g. "hey, my life is full, I'd like to keep in touch, but I'm not in a position to add new friendships right now".

This probably comes off as a rant against social media, but I'm not really anti-social media, I just think the way we find ourselves using it has real, detrimental effects on human relationships, in a way that we don't really understand and are only really starting to see the impact of.