Why did He call him "Lo Ami"?
Radak (8): This refers to the generation of Pekach ben Remalyahu. It says about him "va'Ya'as ha'Ra'ah b'Einei Hashem Lo Sar meha'Chata'os Yaravam ben Nevat" (Melachim II, 15:24).
Radak 1 (8, citing Ibn Ezra): After the 10 tribes were exiled and gave birth to children in Galus, and they remained there and did not return to their land, they are called "Lo Ami."
Malbim: This name shows that it is not his son at all, and the mother is not his wife. If a man tells his [alleged] son 'you are not my son', this breaks also his tie to his wife, since she bore a child through Zenus 2 .
Malbim (8): This refers to the Churban of Yehudah and their exile. This was not immediately; it was after a long time.
What is the meaning of "v'Anochi Lo Ehyeh Lachem"?
Malbim: I will not be to you a father, Ish 1 and husband. Therefore he commanded Hoshe'a to divorce her, and He will expel Yisrael and switch them for another nation.
'Ish' cannot mean husband, for Malbim said also Ba'al! Perhaps it means the most esteemed in a place, e.g. Ish Yerushalayim (Avos 1:4); i.e. the Shechinah will not be among them.
