The theme is rather current. We have turned sexuality into a means of oppression and the vice of this oppression gives rise to violence. Even J.J. Martin argue that Game of Thrones was built around this theme. — Tobias
I agree and want to congratulate
@EugeneW for bringing it up. The incels do tend to turn their sexual frustration into violence. Now, sexual violence is nothing new, but to murder women out of sexual frustration is NOT something we've seen in the past. It is new, historically, a deeply troubling development. It's a new level of perversion.
Another 'theory' is that of Michel Houellebecq in his Elementary Particles: sexual
liberation during the 60's and 70's led to high sexual competition between males, and between females, with the most attractive people screwing all their content and less attractive folks living in eternel sexual misery. Freedom leads to inequality between the haves and the haves not, now applied to sex as well.
The tittle of Houellebecq's first book is also about that: Extension of the Competitive Domain ie an extension of competition from the sphere of production and consumption (under capitalism) into the sphere of reproduction. Like an extension of capitalism to sex.
This theory works well. It explains the nostalgia for some idealised past when young folks were only trying to find a mate for life, and when therefore, while the attractive ones would be taken by similarly attractive persons of the other sex, the less attractive ones could also mate with less attractive persons of the other sex...
Now, in a competitive sex scenario, even the less attractive people have their eyes set on the most attractive people of the other sex, and there lies the problem. The sex game is open (or so they've been led to think) so they want to compete. Note that the incels are obsessed with the most popular girls. They've given a name to them, Karies? They can't let go of them, while in their idealized past, wise unattractive boys would think something more practical eg: "I can't fuck a princess, 'cause they are for the princes, so I'll fuck my less attractive neighbour instead. I'd rather get a paycheck than wait to win the lottery."
If we all want to win the lottery, we'll all end up unhappy and frustrated.