Alpha female, like alpha male, depends on such a sense of innate superiority that she's probably not aware of her status. While she would be effortlessly talented and capable, she would need a reduced capacity for empathy, because otherwise it would derail her.... Achievement is the focus of alpha female's life; anything else is secondary. She does not obsess about relationships. She is dominant: if she married alpha male, there would be a bloodbath.
The toughest action heroine in science fiction must surely be Ripley from the Alien movies, and sure enough a bloodbath ensues wherever Ripley lands. But it is only when she arrives on the male-only prison planet in Alien 3 that the clash between alpha males and alpha female becomes evident. As to romance, there ain't any. Not for Ripley. Maybe her hair isn't long enough?
Can alpha heroines have romances? The only alpha heroine who came close was Trinity in The Matrix. And even though she finds love with Keanu ... erm, Neo ... he's hardly an alpha male. He flounders about like a lost puppy for much of the first film while being shown the ropes, and it's Trinity who comes across as the more powerful one:
In futuristic or a action stories, sometimes the romance doesn't get the attention it deserves because there's so much else going on. The heroine's finding lost treasures, stopping the spread of killer viruses, or otherwise saving the universe and making it safe for mankind. Sometimes the romance has to come second to more important causes. But do you expect the romance to come first?