Greek tragedy - a literary composition written to be performed by actors in which a central character called a tragic protagonist or hero suffers some serious misfortune which is not accidental and therefore meaningless, but is significant in that the misfortune is logically connected with the hero's actions. Tragedy stresses the vulnerability of human beings whose suffering is brought on by a combination of human and divine actions, but is generally undeserved with regard to its harshness.
OK, how about this? Maybe your interpretation has to do with whether as a viewer you're Enniscentric or Jackcentric.
If Ennis is the tragic hero, then it's HIS tragic flaw -- his refusal to be true to himself and Jack -- that leads to his tragic fate. That is having to endure the love of his life dying (which could be one way or another; the uncertainty only adds to his suffering), and accept the knowledge that he missed his one chance to be happy, that it's largely his own fault -- there's that logical connection with the hero's actions -- and that he will be grieving for the rest of his life (a fate undeserved with regard to its harshness, if you ask me).
If Jack is the tragic hero, then HIS tragic flaw is his openness and hope and optimism and willingness to take risks. I know, doesn't sound like much of a flaw, but in a society as intolerant as theirs, it becomes one. That interpretation supports the tire-iron conclusion, because it's logically connected to the hero's actions, whereas a roadside accident is not. That his suffering is of undeserved harshness, in that case, goes without saying.
