This is what the culture teaches boys. If some escape learning it due to active parenting, etc., then they are the exception rather than the rule. Read Peggy Orenstein's Boys & Sex for more on this. She interviewed over 100 boys of varying ages over several years and gives a sensitive (but also disturbing) accounting of how the culture is harming both boys and girls with this kind of cultural indoctrination, which is part and parcel of a patriarchal dominance hierarchy.

"Young American men also report more social pressure than other nationalities to be ever ready for sex and have as many partners as possible; feel a stronger stigma against homosexuality; and receive more messages that they should conform to rigid gender roles in the home and control their female partners, even to the point of violence."

Orenstein, Peggy. Boys & Sex (p. 13). Harper. Kindle Edition.