Ennis to me is a classic passive aggressive, (I hope I'm using it correctly). It was too late to go to the sheep, he stays in camp, Jack's offers the tent for the night, he chose to sleep outside, when the fire goes out, instead of relighting it, he makes noises knowing full well Jack wasn't going let him sleep in the cold. Jacks makes his move, Ennis takes over. I may sound cynical, but I'm not, These two were headed for a collision, (using a term that one of our brokies coined in his own tread), that led to what happened that night. JMO.
Yes,you're right in that the collision was unavoidable between the two of them,and that they have been looking for them some time ago.But for me the problem isn't as much about words and/or actions they did that night,but as about many former others...I mean,they have been sending signals in many ways long before,what was more evident in the hours prior to FNIT.In Ennis case,the first move would never have been done,and Jack was afraid to scare him if his own more open and bolder way of being led him to a too sudden approachment.
So,that afternoon they began to speak,to make jokes...and to drink during hours and hours.Ennis left his duty of going up the mountain with sheep to be with his friend,both consciously and unconsciously;maybe he knew that alcohol takes a lot of inhibition away and he played the game until the end.And Jack didn't ask him to do his duty because he also wanted to be with him,so,in exchange,he full Ennis can with whiskey or gave him the bottle again and again,and the other accepted; Jack also knew the alcohol effects,and how this could help to his intentions,so,he also played the game until the end.
And in this end,both of them were drunken but not enough as to not knowing what could happenned,what Ennis wished and was afraid about at the same time...For this reason,he didn't want to go to the tent from the beginning,until the cold-yes,I'm innocent here,but I guess the cold made Jack ask him to enter in the tent and made Ennis do it,in spite of his fears...-until the cold obliged him to make what he wished,and what he knew was going to happen soon.It's to say,for me,the sharing of the tent was an innocent and logical conclusion to some former hours that led to FNIT,during which their behaviour was premeditated and,so,not so innocent.