As a general rule for cards that have a male/female relationship I have the following view:
The masculine energy is one of external leadership and nurturing. The Emperor commands the armies outside of him. He sends them away. In the sense of human sexual relationships, the man's role is to send his creative power out. In the classical role of man, he goes out on the hunt, he goes out to work, he joins the military to protect his family. -- His weakness is the coldness and loneliness of keeping himself distanced and separate.
The woman, on the other hand, pulls things closer to her. She nurtures from within. In the human sexual relationship, she receives within herself. In the classical role, she stays within the home, brings the children to her breast, etc. -- Her weakness is the intoxication of absorbing everyone else's problems within her. She "worries herself to death" over issues that are not her own.
Ok, that being said, when a man, in a relationship, will take on the role of Empress, it seems to me he'll start taking things to heart. He won't do the manly thing of pretending to listen while he thinks about grabbing a beer. Instead, he'll really allow the words inside of him. It will probably be a new experience for him, and it may intoxicate him to some degree. But if he's classically a very closed-off and cold person, it could indicate a huge turn-around.