When I saw the quote about facing both ways, I thought of the god Janus. I though he just looked forwards and backwards, hence past and future and 'January' but I looked him up. This is quite interesting, I think.
by Micha F. Lindemans
Janus is the Roman god of gates and doors (ianua), beginnings and endings, and hence represented with a double-faced head, each looking in opposite directions. He was worshipped at the beginning of the harvest time, planting, marriage, birth, and other types of beginnings, especially the beginnings of important events in a person's life. Janus also represents the transition between primitive life and civilization, between the countryside and the city, peace and war, and the growing-up of young people.
Janus was frequently used to symbolize change and transitions such as the progression of past to future, of one condition to another, of one vision to another, the growing up of young people, and of one universe to another. Hence, Janus was worshipped at the beginnings of the harvest and planting times, as well as marriages, births and other beginnings. He was representative of the middle ground between barbarity and civilization, rural country and urban cities, and youth and adulthood.
Though he was usually depicted with two faces looking in opposite directions (Janus Geminus (twin Janus) or Bifrons), in some places he was Janus Quadrifrons (the four-faced).
 Myths Wikipedia
I think she is looking back into the past during the novel, and by the end of it, she is ready to deal with the future. I also agree that it is matter of home and family, stability and normality, compared with the rest. Mutz puts it well.
Mutz saw only a new order, a new empire, coming to take its place among the old, and how he wanted to be inside the circle, and not outside, with the maneaters, handmade angels, narcophilic visionaries and Bohemian warlords. And how it was tearing him apart to know that Anna was outside that circle, and though she would hate this desolate place of madness as much as her wisdom told her, she found a source in it she couldn't do without.
But I am also intrigued by the reference to Janus in terms of transition. As I have stated, I think that is what the book is about, on several levels. So maybe she is the axis in that way. But also, I agree with Liz's point. Each of the three main male characters has to deal with his responses to her.