Good question! Like life, no one can know the answer?
Relationships are rare as reality is between two individuals as a couple!
Relationships... is not only about sex (even if that mutual sex can help!!), as there is spiritual connexion too that Ennis and Jack became to know with each other being together at times: (in too rare possible times!!
Mutual caring as with them can be helpful, but social non-fears (hopeful for life) and fears (being killed because you are gay man/men) were too still crystals to both men. .. which both could not disolve and solve. Too scary, unfortunately most times were each of their lives, even together!!
Religious, social, cultural, anti-gay laws, etc., and even persons like their wives as well as potential murderers of gay men, as that and more did not help them free themselves and become a real couple in public nor in private, beyond the Brokeback Mountain (and note that Brokeback was Brokenback); even on Brokeback Mountain as somewhat a heaven as a canopy or a tent, not all their cares were sufficient for each and together, since others like Aguirre looked at them creating a turbulence in their lives even then.
Isn't love an advancing thing?? Singularly and as a couple?? Can we wish that Jack had settled down with Ennis, yes we can be wishful but fear of danger was too great for him as well as for Ennis!!
No one can know the answer to a good relationship, at least Ennis and Jack tried their own way, thank goodness!! They were trying in moments d'occassions; yes, as occassional times!! Even among straights couples (married man and woman), that is so too, most often as ??!!
At least, Jack had as Ennis did too, some mutual joys as blessings being with Ennis on earth as a bit of heaven!!
Why couldn't Jack learn to just be happy with things as they were after Brokeback Mountain? We all wonder...
and hope for thruth and life?? Does this make sense?? Maybe?
Hugs!!
!!