So naive.
I was in a women's refuge some years back.
Around 80% of the women in there were pregnant. Various stages, and for most of us the abuse started in pregnancy.
So the choices were abortion (again, we were at different stages, some very early, some very late) or being tied to an abuser for life. A woman can decide to give a baby for adoption, but the father can easily block that and keep the child, then use it to further abuse the woman.
That's just one instance where your little fairy tale ending all wrapped up in a bow would fail, there are hundreds more instances where its not so easy.