I think I gave a pretty reasonable answer to this yesterday.
It's important to remember that Huma Abedin did not marry Anthony Weiner. She married Anthony Weiner (D-NY), and will do whatever it takes to keep him in office even if it means constructing a fictional "happy marriage" with him and humiliating herself in public.
Once his political career ends, she'll drop him like a pair of old socks and the sham marriage will reach the end of the tracks. See Tipper Gore, Elizabeth Edwards and Maria Shriver as perfect examples of how these craven, pathologically ambitious losers operate.
I think doing whatever it takes goes even further. I do not believe she is pregnant. I think this story is concocted to garner sympathy. Whenever the heat really starts to build up they will play sympathy card number 2-she suffers a miscarriage from the stress.