On my 40th, I didn't formally invite anyone, or throw a party for this reason. I invited a tonne of people to my 18th. It ended up me, one friend, a work colleague who just tagged along as he happened to bump into me beforehand, and another friend and his girlfriend who I could tell didn't want to be there (I didn't know her).
My 21st, 'best friend' dropped out as apparently got the day wrong. Housemate who I saw as a friend seemed really annoyed at being invited - the day before came to me asking for the address of the venue in an angry tone, wrote it down, said her and her boyfriend would come then didn't show up. Everyone else bar two that I invited didn't show up either so just me, one friend and my boyfriend at the time. One of those friends invited a bunch of her friends, and plenty of them showed up so the party went ahead and was good-but with a bunch of folk I didn't know!
My 40th, I booked an act at my local pub. Me and landlord went halves on the cost. I put on fb that that was what I was doing, that I had two spare beds and a comfy sofa if anyone wanted to stay over. I sent text invites to friends who weren't on fb.
One 'friend' who'd flaked on previous birthdays, lots of nights out and many, many other things I'd organised or invited her to was SO annoyed that she didn't 'receive an invitation' (neither did anyone else!) that she fell out with me! The last thing she DIDN'T flake on, she'd turned up 3 hours late, drunk out of her skull and left after 30 minutes. She'd gone to a pub beforehand, and bottles of wine were on offer so her and another friend had sank three between them and 'lost track of time' (good riddance).
On fb, I'd say about twenty friends responded saying they'd come. Old work colleagues, old friends, others-I have a small family.
I reserved seats for those who said they'd come for definite.
On the evening, one very new friend attended and me and him are still close now (neighbour). One friend who'd originally declined but had other plans fall through on the evening came. One of my oldest friends-who proceeded to get so drunk he almost ruined the evening (my brother in law who is very no nonsense and old school wanted to punch him!) and he broke one of my new birthday present glasses, squashed my cake...
My DP at the time came with her sister, sister's DP and another friend. And my Mum, Sister, Sister's husband and nephew also attended. Nephew had work at 0700 the next day so didn't stay long. 11 people and many of them not even 'me' people.
Dad didn't come as the act 'wasn't his thing' (he lives 5 mins away and could have turned up for one drink, surely?!)
One couple I invited cancelled on the morning of the event because their cat was very ill and needed to go to the vet-which I totally sympathised with, until a mutual friend told me that it wasn't true-the actual reason was they'd had a drunk en argument the night before and were still reeling from it. They weren't local (an hour away) and I'd said I'd pay for their taxi back if they didn't want to stay over-still didn't attend.
People suck. I am on my own now and although I do get lonely, it does help to remember things like this.