I understand OP. During my lifetime so far I was a child who didn’t enjoy socialising and we didn’t get to do that sort of thing outside of the family, so my childhood was just looking after my younger siblings.
I was then as a teenager a lone parent with no support at all and no opportunities to make friends, people will say there are mums on the school run etc yes there maybe but doesn’t mean they speak to you.
I got a dog, that’s supposed to help, all it actually meant is people with dogs crossed the road so never made a friend that way.
I then had a career, whilst being a parent, but made no friends that way either and once work was over had to do the parent things.
i then met my partner but work meant he was away Mon-Fri every week so weekends we spent together so even if I had of had friends I’d not have been able to see them then and my peers by then had younger kids and husbands etc. My child grew up and left for uni and I’d just be in the house alone all week every week.
I’m now in my 50s. I am estranged from my family, the only contact I have is a phone call with one parent once a week. All my siblings, nieces, nephews, cousins, aunts, uncles etc do not have any meaningful contact with me. I did try texting some of them a few weeks back, was really anxious doing that even, but all that happened is I had a nasty comment passed on to me by the parent I speak to on the phone from a sibling and I ended up crying for a week. So I won’t be texting again.
My one best friend since school now no longer ever wants to see me. I live with my partner still and my adult child has moved back in with us due to col. they both work full time and have their own hobbies so I’m still alone.
I have nothing to say that will help or be a comfort but just to let you know you are not alone, many of us know what it is like.
And for other people commenting yes I’ve tried classes and coffee mornings but it doesn’t work out. and going out seeing groups of happy families makes it even more heartbreakingly sad as I feel even more alone. I try to say hello or good morning to people as much as I can and I don’t even usually get a response.