The ideal of brotherhood of man, the building of the Just City, is one that cannot be discarded without lifelong feelings of disappointment and loss. But, if we are to live in the real world, discard it we must. Its very nobility makes the results of its breakdown doubly horrifying, and it breaks down, as it always will, not by some external agency but because it cannot work.
The common erotic project of destroying women makes it possible for men to unite into a brotherhood; this project is the only firm and trustworthy groundwork for cooperation among males and all male bonding is based on it.
We must love one another, yes, yes, that's all true enough, but nothing says we have to like each other. It may be the very recognition of all men as our brothers that accounts for the sibling rivalry, and even enmity, we have toward so many of them.