Sorry Browneyes, I was too sleepy to stay online and Stacp I'm Ok with most of what you say, the "charade" part!
The grieving of Jack is in two steps. Well, it is my point of vue, a little particular maybe, so be patient, it might be long! After the second meeting we see Jack getting better and better when Ennis is getting down. After the divorce it became the opposite. Jack went to Riverton in pure excitation and he made two mistakes:
- First he went because he thought he could be a cure for his friend's pain and he discover he is the cause
- Second he asked his way at ten persons.... his place was "out of nowhere" not in Riverton, see how Ennis see the car that pass away
So there is a break, the dance is over, Jack received his second bad punch. He is not going to Mexico by lust, he is trying to quit Ennis! Jack is an abused child (remember what hapened when he was four years) and like all the abused children he is in the power of the hangman, John, his father. Ennis is the opposite, he is under his power too, but that is the way of life. With Ennis, he is like a child and he could not bear to be forlorn a second time. In Mexico, he try to be a man, he is not having sex or fun (look his face), he take the post of his father and he, himself, will abuse a child, the hustler, a willing one. First step of mourning, he takes a mustache a virile attribute but loose he smile, we shall never see him happy after.
The second step is during the stroll that follow. Jack try again to cure Ennis of his sadness, as always he jokes of himself, of his life in Texas, and it goes. For a moment Ennis opens himself and speak of his fear, that is the only time! But Jack is afraid now and his answer is elusive. He said "maybe you should leave" and he he would have said "Yes, I know that fear, when I met again Aguirre I was so terrified that I ran away down to Texas" Ennis understand that Jack is joking with him and burst out in rage.... "Jack, f** Twist". It all tenderness at the second meeting but now it is a leaving. Jack understand that he will never be anymore the cure for Ennis and that was the core of his desire for him. That is why he is not only grieving, he is dying: Randall is too late, Jack has not enough life in him... "sometimes I miss you so bad I can hardly stand it!" that is not a figure of style, that is pure truth
As I said, it is my point of view, others are possibles!