It's only a little harder to make friends when you're older because everyone else has consolidated their daily life by then... they have a group of existing friends, a job, maybe a family. It doesn't mean they're closed off to you, there's no sense allowing yourself to get bitter about that.
If you're socially outgoing you can meet loads of people through people you already know, or put yourself in a position where you WILL meet new people. It doesn't have to be pubs and clubs.. in fact sometimes they can be terrible. I've expanded the amount of people I know every time I've moved house, flat-shared, started a new job, taken on something new, accepted an invite out of the ordinary etc. If I were really truly lonely, I think I'd move completely, find new work or join a club or something. Maybe volunteer. Anyone at GAF who is down about this should consider organising or joining one of the meet-ups.
I went on one of those BritGAF meets and it was hilarious, they were all great people. I know those close to each other stay in touch. I met people at the last two eurogamer expos too... the stigma I guess, would be that its a geeky enterprise and you're only going to meet socially awkward geeks there, and to be honest - the first time, that's what I expected, but by and large -- most people are nice. They're sound.
It is sad to read people are basically unhappy. I'd share a drink with any of them and any of you. I believe in spreading the spirit of Andrew WK.