One can easily make the case that she saw the career value that being EH's wife would bring her.
You get the feeling, reading various biographies and EH writing about her in letters, that there was a calculation and ambition in her decisions and behavior re dating and marriage.

Of course he was a megalomaniac, alcoholic and an abusive general ass***e. She decided that hey, "I will put up with that to further my career"

For that, yuck.