Yes! I think this is part of the "ying and yang" aspect of their relationship.
Jack is optimistic, wants things to move forward and even if he is afraid (of homophobia/ violence, etc.) he resolutely does not want the fear to control their lives. He also wants to be significantly more honest about their relationship. I really don't think he likes sneaking around behind Lureen's back, etc. I think he regrets ever having to marry her. He'd rather get an honest divorce and be completely true to Ennis. So, yes, he would certainly "fix it" if he could.
So, Ennis is the opposite. He's the pessimist (he would probably say, the 'realist') and tragically lets his fear control their relationship. He's stuck in one place and is paralyzed in fear and confusion over how to move his relationship with Jack forward. His fear consumes him so much that it manifests itself physically in his posture, his silence, etc.
These aspects of their personalities remind me of the old symbolism discussions back on the imdb boards. Jack as the wind/ air (moves, shifts, changes, adjusts, is the dreamer "has his head in the clouds", etc.) and Ennis as the earth (static, rigid, silent, stubborn, etc.).
Lately I've had a new thought about the ambiguity of the film's ending and the line "if you can't fix it you've got to stand it." It's really important that this is the last line of the book I feel. It becomes Ennis's life sentence in many ways (he imposes this on himself and unfairly on Jack) and he has to live under the burden of this after Jack's death, because he's run out of chances to "fix it" with Jack just as he's reached the point when he's desparate to fix it.
Well, Jack's heartbreaking line in their final camping trip echos this line-
"Sometimes I miss you so much I can hardly stand it."
Lately I've been hearing Ennis's last unfinished sentence as a response. Something as simple and symmetrical as "Jack I swear, sometimes I miss you so much I can hardly stand it."