The first stanza opens with the breakup of two people that were once in love or infatuated with one another. With Byron, it's difficult to be certain. Yet, there was feeling there at one point in time and the first stanza incorporates this into the splitting up process. I have always read line 3 as a type of ambivalence about the breakup, in that there was not full commitment to it, but also an understanding that the relationship was no longer tenable.