Men have been taught not to approach women in public unless it's online in a dating app. Women have always been taught not to approach men.

So no one is having relationships except for a very small portion of people who are disproportionately physically attractive.

Pair that with the hypergamy that women are doing where they only chase men out of their league now for the most part and it makes things that used to be normal and taken for granted like getting married and having a family exceptional jewels that are hard to come by.

There are multiple reasons for this. First of all due to the fact that a lot of infrastructure is based around cars society actively looses places for people to meet and hang out(I think this effect even has a name, but I'm not sure). Lack of places to interact with other people, and therefore lack of social interactions, causes a rise in loneliness. Then theres the problem with how men are supposed to act. We get told, that we shouldn't "ask out" women in every day life, since its now considered creepy. For me this causes a certain type of being not sure where and when it is OK to ask someone out leading to me not doing it since I don't want to get labeled as a creep. Don't get me wrong, I don't want to blame women for the male loneliness epidemic and there devinetively are a lot of men beeig creeps and asking someone out in absolutely the wrong situations, but this is something that needs to be said to understand the male loneliness epidemic. This also causes dating to take place online. Now the problem is, that online dating fucking sucks. Dating apps are useless, as long as you don't want to sell your kidney to them, since they want you to keep using it. If dating apps were somewhat usefull they'd be out pf buisness quite fast.

The atomization of society. The process of a society breaking down into smaller, isolated units, where individuals are self-interested and self-sufficient. It can lead to a feeling of being alone even when surrounded by people.

What makes you think this is a gendered thing?

Toxic masculinity makes men feel like they need to be strong independent and suffer silently.

As for the other side of the coin, i would guess the Women Are Wonderful Effect.

I know Jordan Peterson has a lot of followers. He says it's the women's fault men are lonely. He says men are their victim, pictures women as evil while men should be on top. This creates an even bigger isolation and creates sex offenders.

In Japan and South Korea there are many men who are isolated because of videogames and it's online culture. They have a relationship with a Nintendo character of AI on their phone (no joke).

Because a lot of lonely men are on the internet, it's not a correct representation of the real world. Doesn't change the fact there are many non the less.

Just because there are many different cultures accessable for anyone through the internet, it's easier to isolate yourself in such a culture. Whether it's on reddit, 4chan, through games, forums or other social media groups. But it keeps you off the streets, away from real socializing, learning to behave, how to talk to a girl, find a hobby which isn't on your computer, meet real friends.

As is echoed a lot in this entire post of replies: therapy isn’t really mentioned here. And that might be a key when it comes to male mental and emotional health.

Traditional masculinity dictates that men don’t share their feelings (with the exception of anger and aggression because that’s not a feeling that’s just being manly). Sadness, despair, loneliness, depression all will be commonly bottled up and left untreated which leads to deep-seated feelings of isolation. The cure has to be a change in social norms, including decoupling the ideas of being socially vulnerable with being feminine.

This is a gross generalization of the issue but it definitely describes my experience with it.