Yes, that's why the scene where Ennis recalls the horrific memory of seeing the brutally murdered Earl is such a crucial scene. That scene reveals everything. It tells exactly why Ennis is so afraid, it tells why Ennis is the way he is, and it make us sympathize with Ennis. It really delves deep into Ennis' character. That scene shows us how much Ennis loves Jack (something we already knew), but it makes understand exactly why he thinks he and Jack must live their lives apart. It's clear he never wants to be apart from Jack, but he's in a catch-22. He fears what could happen to both himself and Jack in such a cruel and oppressive society. That's the whole tragedy of this beautiful love story. These boys are soulmates, they have true love, something that few people ever find in this world, and they know it. But Ennis' fear of taking the "road less traveled" causes them both to suffer immensely in their lives. In the end, he realizes he should have just "lifted the sail and caught the winds of destiny", he shouldn't have let his fear bind him and chain him because true love is more important than anything, he realizes all the misery he and Jack had endured over the past twenty years because although they were destined to be together, society forced them apart. If Ennis could start again, if he could go back twenty years, this time he wouldn't care what restrictions society imposed, he would find a way, he would have never said goodbye to Jack from the beginning.
I think in a way, Ennis wanted to protect Jack, when he saw that flash of Jack being murdered on the phone with Lureen, that was his fear, ik hope to believe that he wasn't affraid to love Jack.
On Jack's question to build a ranch together and go live there, Ennis told the story of the two man living together and one was murdered.
I think that is also why he kept there lives apart, to protect the love of his life.
(hmm very difficult to express myself in english, i hope you know what i mean)
One other thing, and i don't know if it's being discussed before or not (i'm sorry if it is, so much to read here)
When Ennis finds the shirts in Jack's closet, Jack's shirt is on top of Ennis's, when we see the shirts ín Ennis's closet Ennis's shirt is on top of Jack's.
I think that was the moment you knew Ennis made peace with himself as he embraced Jack with his shirt.