I don't believe this is a proper way of trying to explain "loose ends" in
the Torah.Even though he claims not to be minimizing Sarah's piety- after
all, it's not G-d she didnt believe, it was Avrohom - but not believing that
a prophet has had a prophecy from G-d, - and she knew he was a prophet - is
hardly a show of piety.
Besides, the idea of a woman moving out of her home to her friends because
of a disagreement with her husband, is something out of the '90s, not
something you hear about happening years ago. Trying to understand Torah by
using our society as a frame of reference doesn't usually work well.
As to finding a source from the Midrash, that Sarah died because of grief
over the Akeidah - thats a long shot from saying that she separated from
Avrohom Avinu because of it.Something that drastic should have been noted by
the commentaries, and till most recently, nobody ever dreamed of saying
something to that effect.
It may be true that Sarah couldn't handle the idea of sacrificing her son as
well as Avrohom, which may be why he didn't tell her about it. But it seems
highly improbable that she would have harbored that resentment around,
afterwards. Remember, we are talking about Sarah our Matriarch. There are
other
explanations to that Midrash anyway, see Rav Chaim Shmulevitz, Rav Yaakov
Kaminetzky (Emes LeYaakov), Nesivos Shalom,among others.
As to the fact that Yitzchak was still grieving 3 years later when he
married Rivkah - I'm not sure how that supports anything. Rashi explains
simply
that usually a man is comforted over the loss of his mother through his
wife. Yitzchak had no wife, and was therefore not comforted till he
married, albeit 3 years later.
Concerning the original question, where was Avrohom coming from- Rashi,
Ramban and others explain that they had moved to Chevron 12 years before the
Akeidah.Avrohom traveled frequently to Beer Sheva,however, to care for his
AiSHeL tree or hotel.He may have come from there now, or Ramban says he came
to eulogize-not from anyplace else but from other activities.
Ephraim Nisenbaum