Look how Jack is staring at Ennis, in disbelieve ,and love just before the nuzzle.. 

Oh my goodness hpv, thank you!! I think this might now be my very favorite image from the movie. So true--the shadows, the eyes open/eyes closed. . . . It really mirrors their facial expressions during SNIT, I think. Jack looks at Ennis and draws him in, and once Ennis relaxes into it, he has the same expression with eyes closed and mouth open, just drinking in the unbelievable love he feels in that moment.
Thanks, Esme, too, for pointing out that Jack has his eyes wide open here--he faces the situation head-on--while Ennis has his eyes closed, unable maybe to face their love.