The number one most masculine trait is security and confidence.

The proud cuck lets his girl fuck other guys because he knows she'll come back to him. He knows that no matter how many dicks his girl tries, his is the best.

In fact, by consuming the deposited man juice inside his girl's orifices, he obtains the masculine essence of other men, weakening them and strengthening him.

Cucks are the manliest of all men.