Adam Clarke on Jeremiah 2:2

I remember thee - The youth here refers to their infant political state when they came out of Egypt; they just then began to be a people. Their espousals refer to their receiving the law at Mount Sinai, which they solemnly accepted, Exo 24:6-8, and which acceptance was compared to a betrothing or espousal. Previously to this they were no people, for they had no constitution nor form of government. When they received the law, and an establishment in the Promised Land, then they became a people and a nation.

Wentest after me - Receivedst my law, and wert obedient to it; confiding thyself wholly to my guidance, and being conscientiously attached to my worship. The kindness was that which God showed them by taking them to be his people, not their kindness to him.