The incel question is the result of modern sexual morality being incoherent. Since consent is the ONLY thing that matters and "legitimate consent" is (re)defined arbitrarily by elites every day, there is no possible justification you can give to an incel for his status.

"Why am I not fuckable?"
"You're socially retarded and fat."

Past: "Fuck, I gotta git gud."

Now: "WTF, don't you hate body fascism and neurotypicals? Why don't the rules apply to me?"

Since subjective feelings and standards for consent are socially constructed, the whole thing reduces to Will to Power. Hence: radical incel terrorism.
(terrorism doesn't work without powerful backers, but this can't be permitted to become common knowledge in democratic society)

Which is to say: The incel understands that contemporary sexual mores could just as easily favor him, with the exact same philosophical justifications. (This is literally what MRAs are)

What we have is a legitimacy crisis.

Liberalism is built on "Non serviam;" it's never easy for a liberal society to explain the "why should I accept my fate?" question at the best of times.

In the current year, they can't even consistently reason why consensual sex should be licit, let alone why rape is bad.

Where is the political formula to assuage the incels that their superiors actually deserve to be superior?
"Aristocracy is justified because they protect you"
"Capitalism is justified because they take risks and work hard."
"Tumblrism is justified because [???]"

The final note on the incel terrorism question, and terrorism in general:
http://www.socialmatter.net/2016/06/24/mass-shootings-make-sense/

Like I've said before, the death squad is the most democratic institution ever invented.