An Alpha male is a man who owns himself, a leader of the pack. He is internally-driven and certain of who he is and what he wants. It is the very essence of masculine energy so it's no surprise that feminine energy finds it so appealing.
The downside for those who are in relationships with that type of guy is because so many women respond primitively to his darker, masculine energy, he has more choices available to him and is often unfaithful. Perhaps the best real-life example of this scenario is actress Sandra Bullock and her ex-husband, motorcycle bad boy Jesse James, who publicly split after his serial infidelity was revealed in 2010.
Men who feel like they are constantly in a power struggle with a "very Type A female" may decide to tear their women down a few notches to tilt the balance of power back in their favor.