They say that behind every great man is a great woman. Some woman find themselves fulfilled by being their husband's needed support and help-meet. Today this is an old fashioned idea, but the truth remains that it is a woman that makes her man "master in his house", and no man can be master unless she decides to let him be. Candida is depicted throughout the play as being the "ideal" of a strong woman, and it would have been a pathetic conclusion to see this woman throw away her marriage vows and integrity to run off with a coward of a poet. It's only weak women that choose passion over commitment, which is why we have so many families with children from who knows how many fathers. Truly, our human nature desires a more exciting ending and would totally understand if she had chosen the poet, but Shaw is presenting her strength and virtue through the choice she made. It would be an incomplete conclusion to his theme if at the end she became less than the woman she was.