It's not like Jack did'nt have a point. He was as human as one gets. Obviously, this is something that had nagged at him for a while. He senses a difference in Ennis not"coming away" as easily as before. He feels that time is slipping away though it's time that's of the essence. Tired of their love life being played out secretly in the cold winds of the mountains. I feel he had concluded that even if Ennis had no obstacles in his way, that Ennis just did'nt want the sweet life with him. A big rejection from Ennis he's had to accept though he's still trying. He informs Ennis that he could hardly stand being apart , searching for a response to his effort.
Jack had invested so much time hoping that his words and actions would be enough to show Ennis the depth of his love. But Ennis had it all compartmentalized in his mind. Time for him and Jack was time for him and Jack, but it must always end till next meeting , otherwise he would be showing Jack that he needed him, craved him even. Keep Jack on a short leash. He could not have Jack thinkin that he was "a boy like him".
The statement "boys like you", was a statement that spoke of a seperation in how they viewed there sexual relationship as well as Ennis still seeing himself somehow different from Jack. Jack heard that. Felt that Ennis was a little too smug and too personal. Pure, natural ,human emotion. If it was an ef'n problem for Ennis about Mexico, Jack really did'nt care. I mean comon, what was Ennis saying? That Jack was somehow weaker? had the lesser control? "queer" perhaps? or whatever he percieved that to mean? actually questioning Jack's masculinity? It's open for speculation, but what ever he meant. it's what finally pushed Jack over the edge. Convinced that this may be the last time he had to tell Ennis how he felt, he Opens up with both barrels, something he had always feared doing in the past, but by now, Ennis owed him a response to his effort.
I think within seconds he prepared himself as much as he could to let go if it ever happened..,his words ,almost a redemption for his pent up sacrifices all those years. The only weapon he had . Those words almost too critically honest for Ennis's denying ears to hear, but how far did he have to push Ennis to get an honest response? It's not like Jack thought Ennis would enjoy what he had to say in any way shape or form,

quite the opposite. Ennis has struck a nerve big time, I just feel Jack felt Ennis should have known what was at stake as an active partner all those years, and acted accordingly to what they both knew. That Jack needed to see and feel that he was'nt the only one human, and vulnerable to this love. . A dance is a great metaphor WW ,and a force of nature indeed... 5 cents Thanx.