Athene is everything that Ginny is not, and Draco possesses enough self-knowledge not to insult his own intelligence by pretending it wasn't deliberate. They lost Louis, and then he lost Ginny, and he retaliated the only way he knew how: by lashing back. Spying for Dumbledore, Potter, and their cronies during the war hadn't made him a better person; it had merely made him choose his enemies and their weaknesses better.
Athene doesn't sleep in his bed. She doesn't even, usually, live in the same house as he does. They'd talked about it before they married, in a perfectly civil, perfectly sterile conversation in which Draco had told her that he needed to be married for the extra credibility it would lend his name and that he didn't want children. Ever. It's not the worst lie he's ever told her. If Athene cared at all, perhaps he would care more. Instead, she had smiled rather coldly and said that suited her fine, and she would need an allowance of at least a thousand galleons per annum, and she would keep her lovers discreet. It usually amuses him in a twisted way that they look for the same things in their women: red hair and an unquenchable zest for living.