This is where it gets muddle for me. That FNIT, was started by Jack taking Ennis hand, but Ennis takes Jack. Was it because he was drunk, was it anger, or was like the shooting of the elk, going to sleep with sheep, was it "no more beans" Was Ennis doing one more thing that Jack wanted?
And in turn found that he wanted it too, because the SNIT was all Jack, Ennis needed to be shown the way, how to make love, and not just have sex, and what to do with these feelings, Ennis had to find this out and Jack showed him.
Jack may not have been good at a lot of things, but Ennis didn't care. Jack gave him something that no one else did.