Martial Obediance
Ovid promotes a sense of duty when he talks about relationships. In his opinion, a man should behave toward his wife with the same level of obedience as a soldier in the military obeys his superior. He's not necessarily saying that the woman is superior, but he is explaining that a man should honor and respect her enough to pay avid attention to her words and attitudes. This is the reflection of love, when a man treats his relationship as an military post, a life-altering duty.
Jealousy
Especially in the third book, jealousy plays a major role. Ovid's primary advice for women is to find creative ways to keep their husbands interested in them. When other techniques fail, Ovid tells them to orchestrate situations which will make their husbands jealous. He does not say to be unfaithful in any way but to simulate a situation which would deserve jealousy. That way the man will continue to need to actively pay attention to his wife.
Unity
The goal of relationships is unity. To Ovid, there is no better representation of this than sex. He devotes some serious thought to how to best achieve unity in bed. Though people can never actually become the same person, they can come close on each level: physical, emotional, and spiritual. The demonstration of this unity is when a couple orgasms together. Ovid despises the thought of having sex but not climaxing together. This theme of unity is paralleled in the different roles which he lays out for men and women. Despite fulfilling different needs in the other person, each lover still should be operating based upon the desire to completely love and to be loved completely by the other.
Sex
As one might expect in a book about relationships, Ovid discusses sex. He does so at the conclusion of the three books, but he also hints at it throughout the entire text. There is hardly a train of thought about an aspect of a relationship which Ovid doesn't end with a veiled reference to sex. Because sex relates all three levels of a person -- spiritual, emotional, and physical, -- it mirrors every other aspect of the relationship. This all but necessitates the constant reminder that after the work of "x" is done, you should do "y" in bed, and so on. Ovid places great value on the therapeutic ability of sex.
