There’s always a reason.
I met a never married, never had kids man in his mid Forties.
He’d been in a 15 year relationship with a woman who already had young teens when they met (he was 24, she was thirties I think).
He did say they’d vaguely discussed marriage once but she’d not seemed that interested as she’d married and had kids young before him.
He also said they became accidentally pregnant but terminated because she already had children. He was mid twenties by then so probably still not thinking about a family of his own that young just yet.
So that’s his reasons for never being married or having kids in his forties.
Then he met me, a lone parent with a baby and toddler. Six years later we are engaged, a first time marriage for both of us.
I’ve only personally known one another never married, no kids Forties man. He was active in the local church community and lived at home with his elderly parents. We dated once, but it was clear that although he was nice, he was kind of sheltered. I suspect he’d never had a girlfriend at all, actually.