Essentially, you're just describing a feeling of "Better Times", or nostalgia. Nothing wrong with that, and everyone has those feelings.

It becomes a problem when people tend to fixate on that, and not realize that time has passed. Not that you can't create those conditions and feelings again, but that life circumstances and everything else really make it impossible to replicate that same thing again realistically.

I think it may serve you better to focus on what about that situation made it great for you, and what practical means you have to create a similar social circle again that will approximate those same feelings. It won't be exactly the same, of course, but it sounds like you have just been feeling somewhat lost without a similar group of people around you.