But they, like Adam, have broken the covenant. They were unfaithful to me, there.
The meaning is very similar, no matter how the passage is read.  In (1), the meaning is that Israel had broken God's covenant, like all mankind in general.  (2) In this, the meaning is that Israel had broken God's covenant just like Adam and Eve had broken it in Eden.  (3) If this rendition is followed, the meaning is that Israel's breaking the covenant with God was like that which had occurred at a place called Adam (usually identified with Tell ed-Damijej, one of the fords on the Jordan river).[18] This third rendition is very attractive to most scholars because it rounds out the list of place-names appearing in this summary of Israel's treachery: Adam, Gilead, Shechem, and the house of Israel (Bethel).[19]  In none of the places here cited, is it possible to identify, except in the most general terms, the exact nature of Israel's transgression.  As Smith put it, "The interpreter may have to be content with the recognition that each was related to the transgressing of the covenant."[20]  Of course, there are some specific things related in the context.