It is interesting to note that in those intense scenes where nothing really is said, it is the music (la musica) that informs us of the emotional context, no? Especially in this scene with Alma after she catches sight of Jack and Ennis kissing -- there is a lull and uncertainty in the melodic line (as if only a drone or a continuo in strings is heard) in that part where Alma tries to recover from what she had just seen.
I'd never really noticed the music in that scene before, but I've just watched it again, and you're so right. I don't know what the technical term for it would be, but it sounds like a kind of "spinning" sound (I can't think of a way to describe it properly) similar to what I imagine Alma would be feeling, like her head was spinning and her world was spiralling out of control. Maybe that's why I never noticed the music, cause it's so much part of the scene...it's another example of the subtleties in the film, and how all the elements of the scenes blend together so well and make everything so real and intense.
Another unspoken moment I just adore is after Ennis says "That's the most I've spoke in a year", and there's a pause while Ennis's words sink in, and they're both lost in their thoughts, but thinking the same thing, realising what a huge deal it is for Ennis to have opened up like that, and what it means that it's Jack he's opened up to. Jack is just so pleased to see that Ennis likes and trusts him enough to confide in him, and Ennis is pleased to have found someone who he can trust and feel comfortable enough to talk to, it's such a sweet moment, both of them silently acknowledging the connection between them

But then Ennis shifts uncomfortably and seems kind of puzzled, or maybe even a bit scared by it too, as if he's wondering what it is about Jack that made him open up to him, and he's worried about what the answer might be. Ennnis then changes the subject back round to the rodeo thing, and the moment is lost, but that silent pause shows them both realising that their feelings for each other were growing deeper
