For the last time, the issue is not the lack of sex. Stop putting so much importance on sex, that's how you get incels that go crazy that they cannot get laid before they hit the magical age of 30, or that they are forever furious because they didn't get laid before the age of 18 like "everybody else". Men lost their virginity past their 30's and started families in their 40's throughout history, it's meaningless bullshit that keeps distracting people from the real problem.
The real issue of male loneliness is exactly that, loneliness. No sense of belonging, no sense of brotherhood, no one to talk to or meet. Throughout ancient history, such places existed, such as Greek gymnasiums or Roman thermae. Those weren't just gyms and bathhouses, those were places where men of various ages and backgrounds met each other, exchanged knowledge and grew as people. Nowadays there's no such places. The closest you'll get are gyms, but those are not only mixed spaces, but more and more people just go there to put on earbuds, work out and leave, which makes them less and less of a social area. Not only do men have less and less spaces to meet at, more and more men lock themselves out of it, amplifying the issue even further.
So with the death of those male exclusive places and the rise of digital isolation, you get men that roam around aimlessly, cannot find their place in life, try everything to find it, including digital detox, and eventually develop depression. Everyone will foolishly associate their loneliness with a lack of sexual partner, but the issue is much, much worse than that. They have no one. Not even other men to talk to, and men need to talk to other men. Men also have feelings, men also have problems, men also have moments of weakness. If they're told on every step by everyone, both men and women, to just "man up" and magically wave those problems away because "they're a man" will inevitably lead to this negative feedback loop to reach it's peak, leading to the rise in male suicide. But of course everyone will point to every possible reason besides this one simple fact, because everyone refuses to even acknowledge it's a problem.
Men need other men, this is the real issue of today's world, and it's the real definition of male loneliness. Lack of female partners has nothing to do with it, and if you keep emphasizing that it is, you're part of the problem.