The Shekinah and the Second Temple+ the Ahava River

a. I have read that the Shekinah (Divine Presence) was absent from the Second Temple. What are the reasons for this?? b. In Ezra 8:15 it says, "I assembled them at the canal that flows toward Ahava" Ahava is spelled with two Alephs. One at the beginning and one at the end. Scholars and archaeologists have been unable to find evidence of such a river or canal with that name. Is it possible that the word "Ahava" is a metaphor?? What do the Sages say about this??

a. Our rabbis explain that the shechina was lacking in the Second Temple (516 BCE- 70 CE) because most of the Jews stayed in Bavel and never returned to Israel. The Land of Israel and especially Jerusalem are always holy, but the holiness shifts into a higher gear when the People of Israel are in the Land of Israel. Like in a true loving relationship, just as the Jews bring out the best of the Land, so too the Land of Israel brings out the best of the Jewish People, e.g. we only get prophecy in the Land. b. The Ahava river is written there with a vav and not a vet (more properly pronounced: Ahawa), and has no meaning in Hebrew, and the Sages don’t comment on the name either.