I don't think Ennis would have ever found anyone else like Jack. First, he just found Jack as a co-worker, then a friend, then, eventually, a lover. At that point, he knew Jack was someone he did not want to lose. When he did lose him, he was devastated. I don't think there would have been another set of circumstances that came together in Ennis's life where someone else would have been his "Jack". Ennis seemed to have no friends. He worked all the time and, when not working, was home with Alma and the girls. He's a lonely man -- has no clue what is missing in his life, but, I think, he realizes something is not right. Life is not complete. The only time that feeling goes away is when he and Jack get together. Finally, he admits to himself he loves Jack. I just don't think he would have ever admitted to loving any other man because the circumstances would never have been right for it to happen. With Ennis, his relationship with Jack is sex, but a WHOLE LOT of friendship, companionship, oneness......