The Emperor and Empress are archetypes of love focused on physicality. In The Lover, we are humans relating to humans on an emotional level, rather than merely physical. Choice based on emotion. Passion.
This is a male archetype. Choice means action. Thus the central figure is male. His feet pointing in opposite directions emphasize the notion of choice. Being between two human beings emphasizes that the choice is of an emotional character. The young woman’s hand on his heart re-emphasizes it.
Is this a new choice? (Young woman.) Or will he draw from previous experience to make it? (Older woman.) What does experience tell him is the right decision? Eros will compel him to make the choice. No matter what, the choice will be made. The heart will be moved.
There is a vulnerability in his position, shown by only his legs being uncovered and exposed. He is putting his neck on the line. The consequences of his choice inviting this or that person in his life will be his responsibility and his alone.
Being the archetype of love it is also the archetype of hate. Thus, since karma is rooted in emotion, The Lover bears the seed of the creation of karma through transgressions of will, as well as positive karma through genuine altruism.