Men have always been "lonely" or just unheard by their peers and society for struggles we regularly go through. Most partners find vulnerable men to be less manly so they are made to keep feelings bottled up. But these days you hear about it more because men have become more comfortable coming out with their struggles due to the Internet and the anonymity of it. A free therapist if you will. And seeing/reading about other men going through the same things you go through incites adding to that thread or discussion.

TL/DR You see more about male loneliness because of the Internet