I think loads of people feel like you, @Wantachangefor2024, even if they have partners and children.
IMHO, it’s naffing WhatsApp groups and social media in general. Lots of people don’t regularly call each other for a chat or meet IRL any more. Plus, the double-whammy of seeing other people posting about their exciting lives, when really it’s all for show and they’re feeling empty inside too.
Then, everyone’s working so hard, and so skint, it can be too tiring and costly to have an in-person social life.
The best thing is to find people via things you enjoy. Are there any local walking groups near you where people bring dogs? Something like community gardening? Could you join a book club? Or go to an evening class? Or online groups for people going to gigs? Even if it’s something you don’t particularly enjoy, it can lead to making friends and then you can develop the friendship by chatting on the phone or meeting up separately.
IME, making friends with people you get on with of any age can lead to making more friends via them and that helps widen your circle.
My mum’s in her 80s and is constantly making new friends.
Don’t give up on having kids. I had mine late 30s/early 40s. No problems.