The sexual urge is the raw material of love. It is a gift that can only reach its potential when it is integrated with the other qualities of love.
It should be realised that in his sexual urge the male is likely to be sensual, whereas the female's sexual urge is more likely to be one of sentiment. However love is not just an emotion, and still less a mere excitement of the senses.
If actions in a relationship are shaped primarily with a view to pleasure, then the person who is the object becomes a means to an end. Love demands that a person of the opposite sex cannot be only a means to an end (sexual pleasure).