Well fine, you can speculate about why she went back there but the essential point was that she wasn't sufficiently afraid of him to deter her from going back there.
I don't really see anything that leads you to think that spousal abuse is the cause for termination of their relationship in August of 1961. I agree that she had some sense of urgency to return to the U S from Kenya but the source of that urgency is speculative.
Is there proof that she went to Cambridge, or just the hearsay evidence from the friend who said she was traveling thorough Seattle on the way there to meet her husband?
Corsi article @ WND re missing six months in life of Ann Obama
http://www.freerepublic.com/focus/f-news/2317622/posts
The abuse wasn’t to Stanley Ann Dunham. It was to his second American wife, American-born teacher named Ruth Nidesand, who lived with him in Kenya and divorced him because of his drinking and abuse.
He then went back to Kezia, his Kenyan wife.