It's one thing being alone, enjoying yourself in the safe haven of your solitude, pursuing your passions and hobbies, furthering your education, working for your dreams or just relaxing, meditating, taking care of your well being. Each day that passes I grow fonder and fonder of this time spent just being with myself. Peacefully and quietly.
In that sense I truly do believe we are ALL meant to be alone for extended periods of time, even the most extroverted and outgoing of us. We'd be wise to de-clutter our lives and drop so many distractions. Devote our energies to the one worthwhile pursuit: wholeness. Peace. Inner calm. Search for meaning.
I also think we are profoundly alone in that no matter how much others love us or help us, our perception is unique, and we're each stuck in these mysterious individual neuron hallucinations we like to call “consciousness”. It's already nothing short of a miracle we can communicate and get a tiny bit of what goes on inside to one another.
That being said we are also a gregarious species. That means we have an unquenchable pull to connect. Even in spite of a lifelong string of bad experiences there's something in us that still craves being understood, being tenderly caressed, feeling seen, appreciated, accepted. Being deprived excessively of these basic human needs is unbearable and people will go to great lengths to avoid it. Did you know many people hire prostitutes just to talk and cuddle? Not to mention sex can be a way of getting a sense of acceptance too.
Then of course there's the problem that you can be surrounded by people and feel extremely lonely. This is usually because pain makes us separate our mind from our heart and our body, and so we are lacking a kind of consolation only getting re-acquainted with our deepest essence can provide. And we keep looking for it externally and it's never enough.
To sum up: I think we all need solitude but no one should have be excessively lonely.
When that happens it usually has more to do with our inability to empathize and care for those who are different. Especially those who don't comply with the expectations of the system. Those of us who need more help, or are struggling. We shouldn't wait for people to always ask. If your question was prompted by someone in your life who's lonely and seems miserable about it you could take the initiative and you'd be surprised how a small kind gesture can go a long way.