Annie Proulx uses that language in her story. Stepped over the line, trespassing on unknown territory. Just means going outside of the box. I interpret his reaction as being positive.
That could have been exactly what Elliott meant; but, he used the conjunction "but" immediately after the dash after "line." That's why I responded the way that I did.
When it comes to telling the truth, we do have to step over the line: but, we need to make sure that there is an actual line drawn to do so.
Ennis stepped over the line when he misunderstood why Jack mentioned Mexico. IMO, Jack claimed that he had been there because Ennis seemed to have threatened to kill him if he found out that Jack had been doing certain things.
I just feel that Jack felt like he belonged with Ennis; but, he did not like the idea of Ennis owning him, that was what Jack was referring to about the "short lease you keep me on."
OT here; but, I allowed. Rick, the boyfriend of Richard to live with me and stay in my extra bedroom in 1988 (Rick did help with rent) because Richard was not supposed to have a room mate in his government owned apartment. Richard did not want me to have sexual contact with Rick; but, Richard had sex with guys when Rick was not around. Rick himself really wanted his relationship with Richard to be monogamous. But, Rick was sexually attracted to me. It was also as if Rick did not know what was going on behind his back. But, Richard actually bragged to his other friends about the guys he picked up in the park and elsewhere and took back to his place.