If you haven’t done it by 50 you never will.

He will continue to be single unless he changes something about himself. Either his outlook or his behaviour. Because realistically if you've been the same for 30 years and it hadn't resulted in a particular outcome, the chances of that changing at a time when there are fewer opportunities is very slim indeed.
It can happen, but most of us don't live in a fairytale where 'the one' has always been out there, and its just a matter of waiting for our paths to cross. Most of us accept that we cross paths with a lot of potential partners and its down to our behaviour and choices whether we turn any of them into our 'one'.
Your brother either doesn't really want a relationship so has self sabotaged, or his expectations are unrealistic because what he brings doesn't correlate to what he wants.
If he is to find a partner he would need to firstly commit to the idea, secondly be realistic about what sort of person may want to be in a relationship with him and be prepared to compromise, and thirdly put the work in to ensure he has something to offer that a woman would want.

My colleague in her mid 40s met now husband who was then about 50. Both of their families were starting to think the same thing you are about them. Neither married before, both were living alone and there is nothing much odd about them, they have been happily married 10 years now. Unable to have children but both would have if they’d met earlier.

My brother similar to yours, not committed relationships, never lived with someone, in his late 40s told everyone he will likely never settle down - possibly to stop people asking - no trauma, he is great with children and I know would have had them if he’d met the right person earlier. He did still date a bit but as far as I know, now late 50s he doesn’t.

Yes I know a man who lived with his mum into his 50s and then met a woman who already had 3 children. They are together still, after about 6 years, and have bought a house together now that her youngest is 18.

I also know another man who never married, had two long-term relationships, one where they lived together but it didn't work out so they split when he was in his late forties. He met another woman via a dating app who had 2 children already, but grown-up, and they have been together 10 years, got married 5 years ago. They are both almost 60 now.

Both nice men. First possibly had commitment issues, but second didn't at all. Just unlucky.

Well- my BFF met her husband when he was 50. He'd never been married, never really had a long term girlfriend. They married and had their first child when he was 57 and their second when he was 59. Been together 24 years now and have a really solid happy marriage. He had just never met 'the one'. Neither had she really- in her early 30s when they met and had never had a relationshop longer than a few weeks.

I’m no psychologist, but I suspect the answer to this lies with your brother and his feelings. It’s not that it’s impossible to meet and sustain a LTR in later life - look at widows and widowers who have another relationship - but is it not likely that your brother is sabotaging his relationships?

At some level, love and attraction only goes so far, and for a relationship to work, both parties need to be willing to find ways through differences. A conscious choice has to be made to commit - or not. As long as your DB chooses not, he is also choosing to be single.

Why does it matter ? Maybe he’s happier the way he is .

Yes, I can think of a couple I know where she was single into her late fifties/early sixties, met someone (a widower) and they fell in love, married within six months and are by all accounts very happy. Only one though out of quite a wide circle of acquaintances. I think it’s possible that your brother will marry but perhaps not likely, especially if he’s unwilling to do the work on his previous trauma.

I think this is a really strange approach from you.

It may be likely, given his relationship history to date, that he won’t meet a life partner. But not impossible, and really not your business. There’s inherent judgment in your post.

In any case, just because there may be some people (and of course there are, I know several, men especially) who have met someone later in life, it doesn’t provide any indication of whether your brother will or won’t.

I think he's going to find it very difficult to live with someone at this stage. It needs a lot of practice when we're younger and more open to learning and accommodating others.