"Lil darlin" doesn't sound like something movie Ennis would say in comparison with book Ennis. Heck, he's not even romantic enough to confide to Jack that he must have it wrung it hundred times thinkin about ya. Now that's romantic.
Then again, that last statement might have been edited out of the screenplay for our puritanical moive goers. If they ever make this into a play, I hope the script does include some lingo left out of the movie, but was in the book. Of course, there is some great dialog in the film not in the book. Now who on here is a good playwright? Anyone bother to volunteer. Becky?? Jeff Wrangler??
Personally, I'd ax Cassie and have more Jack, i.e. Jack having a dream sequence where he and Ennis take a road trip. Of course, it would be too out of character for book/movie Ennis so it would have to be a fantasy of Jack's doing.