I could never see Ennis moving to Texas, Sandy. The post-divorce reunion scene (and to a lesser extent, this scene) pretty much make it clear that no extenuating circumstances would have moved Ennis past his fear.
You're right Chrissi; Ennis opens up in an unprecedented way here. I think Jack is kind of thrown for a loop by this, so he replies with wide-eyed silences and flat little fibs. Then he proposes a simple solution, which (as Katie pointed out) sounds next to impossible to Ennis.
It's been written that heterosexual couples also tend to (mis)communicate this way: a woman will lay out open-ended questions; a man will quickly present a solution. Which is disappointing to the woman, b/c she wanted to fully discuss her feelings and get some catharsis and empathy, while the man has immediately jumped into problem-solving mode. [This is of course based on generalizations; there are variations to this in real life; your mileage may vary, etc.]
Ennis' frustration with this comes out in his rather comical "You're a real thinker there, Jack!" Because Jack has indeed not thought through all the issues that would come with a move — not the least of which is Ennis' pride, as you pointed out, Brokeplex.
All of this is not to say that Jack should or could have intuited all this and come up with perfectly-phrased, healing words. An overriding hardship in the tale is that neither is emotionally or verbally equipped to deal with each other's issues here; they're at their best when circumstances — as back on Brokeback in '63 — allowed for snuggling, riding, light conversation and comfortable silence.