I wish Mr. Lee could read this thread (and other threads like it). He would be so proud of his talent. A good director wants to make a movie where everyone who sees it gets something good out of every scene.
If he could read this thread he would see that each of us came away from the second tent scene with at least a little different interpretation.
Here is mine (it encompasses a little of most everyone Else's).
Ennis has been drawn out of himself for the first time in his life. He is talking more than he ever has. He is loving the friendship of Jack like no friendship he has ever had. He loves Jack, but is not in love with Jack.
First tent scene: Ennis is drunk. Jack brings to the table something Ennis was not expecting, sex. Ennis is terrified of the thought of sex with another man because of what his father made him look at when he was nine.
At first Ennis pulls away as if he had touched fire. Then, in his drunken state, he realizes that Jack is offering him something he has never had ("What are you doing?") Ennis is not queer. He is a man and a virgin, so he takes what is being offered as a young inexperienced man, roughly and violently. It could almost be taken as a rape, (except you can't rape the willing).
He wakes up and feels guilty he has had sex with Jack. He snubs Jack and shoots him a disgusted look as he rides out to the sheep. That afternoon, while riding up on the ridge, there is something eating at his mind.
Now here the screenplay says it is day time giving the impression it is the second day after the tent scene. Ennis comes upon a sheep killed by coyote pack. The sheep had obviously died violently. A look of shame washes across Ennis's face. A shame for the violent way he had treated his friend? A shame for snubbing him for a whole day?
That night, Ennis, still feeling guilty, approaches the tent in a very submissive way, enters and says I'm sorry twice (Yes, I heard it for sure although it is not in the screenplay at all). Jack replies it is all right.
Jack gently takes Ennis's face in his hands and gently and lovingly kisses him. Ennis kisses back. Ennis has given in to this forbidden love.
Ennis and Jack enjoy their remaining time on Brokeback Mountain as two very special friends----with privileges. ;-)
They are off of the mountain...Jack gets into his truck and drives away. Ennis walks about half a block and suffers a gut wrenching pain in his stomach and heart. Ennis no longer loves Jack...he realizes he is in love with Jack and should never have let him go. He will never see him again...he thinks.
Anyway, that is how I saw it. But, like I said, each way it was seen by others is just as valid. Mr. Lee did a great job.