I think I would parallel the poem to a love affair. The speaker, an onion, first is upset that he/she makes the human cry as his layers are peeled away. Then he tries to make up by telling the human that he didn't mean for things to turn out this way...the onion realizes the human is determined to "seek my heart." He is almost moved by this and apologetic...it was not his intention to make the human cry at all. As the poem progresses, the onion becomes angry and resentful that the human continues to peel away layers which makes him/her cry. Why not just stop? Why continue with this ridiculous behavior? Are you a fool? The onion speaker becomes judgemental even and by the end of the poem tells the human that it is not the onion in pieces, but the human.
Sounds like a rather sadistic love affair or at least the peaks and valleys of what started out as a great relationship and ended in divorce. Can you come up with something along these lines of thinking? It might be a fun exercise.