I think that framing "being single" as "having a problem" is the actual problem.

If the problem is loneliness, then I would say that I think men need more meaningful connections with each other. If you're terminally lonely, finding one person to talk to isn't going to fill that void.
If the problem is of masculinity, I would say some guys should take stock of their priorities. It's much more fulfilling to get fit, take care of yourself, and get good grades/have a good job than it is to have the "girlfriend" notch on your belt filled.

I agree with OP in that I think there's a weird insistence that some men being single is this huge problem society needs to come together and solve. If some men get resentful and become misogynists or MRAs, then they're willfully making themselves bigger problems to get what they want, and the solution to that is to not give into whatever demands they have, and to instead ignore them even harder, e.g. we shouldn't start culturally pressuring women to lower their dating standards somehow, in the name of reaffirming positive masculinity and male mental health, or something like that. Not saying that you're saying that; that's just my concern. That's just the only "solution" I see to the "problem" of some men who want girlfriends being single.

There's nothing wrong at all with being single. The problem is unrealistic expectations. The fact that so many straight guys are single also means there are a lot of straight women without a suitable man to date, and they're lonely, too. But they deal with it by focusing on other things, like their career or their fitness, or they get more friends.