This makes me a bit impatient. On the one hand, you could say that it's an instance of patriarchy victimising men as well as women, but on the other, men have long had considerable power to shape the world they live in, far more than women, so it seems to me that if men don't engage in friendships, it is by choice -- even if it is recognised that this is one of the contributors to male MH issues and the higher male suicide rate.
I do think laziness and some vague but pervasive idea that maintaining friendships other than the most basic 'down the pub/work colleagues' situations is 'wifework', is also a big part of it -- as though friendships are some kind of 'women's specialism', like remembering your mother's birthday. I know so many men in their fifties and older who just piggyback on their wife's social life, or who, when not at work, just sit on the sofa gaming or watching TV.
I got to know someone in his early 50s via a former job who used to mention friends, but once I got to know him better, I realised that these were friends he'd had when he was at university nearly 30 years earlier, and whom he'd almost never had any contact with since.
Incredibly, his wife, who had tracked them all down via social media to invite them to their wedding (he didn't use social media, and didn't have up to date contacts for any of them -- he married aged about 35), friended them on FB and apparently relayed him their news, which apparently gave them both the illusion that he had some form of friendship group, even though I don't think he's seen any of them in about 20 years now and makes no effort to stay in contact 'because Wife does that for me.'
Actually, I've just remembered that she also contacted and asked one university friend to be his best man!
Now they're divorced, so he has almost certainly reverted to having no friends at all. He's a lovely man, interesting and funny, but he's just too lazy to even keep up with old friends on social media, far less make new ones. Even if he's lonely, which he is, he's not lonely enough to do anything about it.