Sometimes we have talked about both of them clothings color;they usually wear in earth and air colors,as a reflect of their respective personalities(it's to say,brown and white in Ennis,blue and black in Jack). And also about how these colors in clothings change in Ennis case,almost always when Jack is not by his side (for example,in the conversation with Cassie scene)..Only there's an scene where he wears also in blue when Jack is with him; in the scene of the argument by the river.And even we could say that he's more "in Jack's style"then,because he tries to show his innest fears and thoughts before his lover,maybe for the first and last time.So,is he nearest to Jack then,not only in a physical,but also moral sense of the word?.
There's also an scene where colors meaning plays an important role in the story;the one in Twists home.Everything is in blue or grey,from the house itself to the walls,specially in Jack's room.Mrs.Twist wears a blue jacket and a grey apron,her eyes are blue,but warm and compassionate in comparison with Old Man Twist icy blue eyes;even Ennis wears again in grey and blue,maybe because now Jack is not by the side,this time forever.
In painting,they say that blue is sorrow color and even teachers advice to put a blue shade before painting the rest of the colors if we want to represent sorrow and loss.I think in these last and terribly painful BBM scenes,these feelings are all over the environment,so Ang Lee didn't choose these colors without thinking on their meaning.