It is not only the male-male bonds that the heterosexual society denigrates by propagating it as 'unmanly' ... the heterosexual forces also degrade one of the other strongest -- in terms of nature -- human bonds: that of the mother and her son.

The western heterosexual society -- through its extremely powerful media and entertainment industry -- propagates it as unmanly, to be affectionate towards one's mother. A 'real' man -- as per the definition prescribed by these forces -- while sucks up to girlfriends, wants to keep an emotional/ social and physical distance from his mother. 

Men who are attached to their mothers are propagated as weaklings. However those that are attached to their girlfriends and allow themselves to be subdued by them are actually propagated as 'real' men (straights).