Goodness, but it amazes me to feel such deep emotion for this film and our beloved Jack and Ennis even after all this time. I am almost a year and a half out, and I STILL get that deep ache when I remember that lake scene...
Snavel del Snuit - I can understand your thoughts on this scene. However, my thoughts are that, basically, Ennis is "stuck" and Jack is "deeply sad"....
Jack's sadness jumps out at us and at Ennis when he proclaims, while looking so solemnly forward, that he misses Ennis so much he can hardly stand it.... I think, getting that sadness, longing and pain OUT and to Ennis so that he hears it, releases a floodgate of emotions for Jack, and he can no longer hide them the next day. He is sad. He is lonely. He realizes quite clearly that Randall is a fill-in for what he really wants and misses -- Ennis!!
He misses all that he and Ennis could have been to each other and how much they could have shared together, if only Ennis could break free of his fear, just a little, enough to trust Jack and not look back, but, he couldn't. Poor Ennis... He just couldn't get out of his own way....
I think, in this scene, that Jack is mourning his and Ennis' lost chance... I think, when he says he wishes he could quit Ennis, that he really means that. He wants to let go and he doesn't know how. He wants to let go because, at this point, it hurts him too much to hang on, but, when Ennis breaks down from realizing that Jack might actually leave him for real and for good, it is my thought that Jack then realizes that this is all hurting Ennis much more than Ennis might be hurting him. Ennis is being eaten up inside, and Jack, who, as Clancy taught me, understood love, feels he needs to let Ennis go and release the pressure on Ennis... What Jack doesn't know is that this is Ennis' point of no return. Ennis is starting to understand....
But, as we know, sadly, it is too late....