Alone.

[Scrumpy]

I went for a coffee this morning. 
I noticed three (older) men sitting alone and one woman alone.
The men were mostly reading newspapers .. one was doing the crossword .. The woman was just looking out of the window.. None were using mobile phones..
It would seem that there are many people on there own out there...

[Mups]

Yes,  as you say Scrumps,  I think there are a lot of people on their own.

Depending on where we live, there are often places to go, like day centres, where you can join in with others and chat, have a cup of tea, do gentle exercises, play games,  do puzzles, or have a meal together, etc,   but not everyone can travel to get there,  or perhaps they just don't want to.
But I don't believe everyone living like a recluse, does it from choice.  It's so sad if they are lonely.

I guess different things suit different people though.   You can't make them mix if they don't want to. 
I know I missed the company and laughs I had with my work mates when I first retired.

A local charity near me also offer 'Befrienders'.  These are proper 'vetted' people who will either phone you, or I believe pop in,  and  chat and keep folks company for a while each week.
I suppose that would be a better choice for those who are too frail to get out to be with people.

I am so glad I have got my dogs.  I would be lost without their company.   
I know they don't say much,  but sometimes that can be a blessing,  as they would probably only say
'When are we going out'   or  'where's my dinner.'