Today on National Geographic Channel, on the programme titled "Madlab" they reported that when men and women fall in love, the testosterone level in men fall bringing about a number of changes in men that make them feminine, while their female partner undergo hormonal changes that make them more like men in their behaviour.
Thus, it is again estalished that heterosexuality (i.e. falling in love with women) doesn't make a man manly. The only thing sexual with women that will fall within the purview of manliness would be occasional instinct to penetrate. Any emotional or long term attachment with women or for vagina/ female body is feminizing and the ancients/ non-western societies have always known that.
In Greece e.g., while men were required to procreate/ penetrate women to be eligible for manhood, over indulgence or desire for vagina was seen as feminine/gay.
All over the world, men in manly pursuits like warriors and sportsmen were required to keep away from any kind of contact with women -- whether sexual, social or emotional in order to, as it was long known as feminizing, and harmful for those pursuits. Pehalwans in India, e.g., were, traditionally encouraged to go without marriage for their entire life -- just like their deity, Lord Hanuman -- the warrior god of manhood.