ennis is a bass baritone and jack a tenor..
now what does this say..?
we have our next big meet ready, folks..
A bit off topic but for better understanding
Bass Baritone is not the deepest male voice but not far from it, however the tenor has the highest tone in male voice range.
One example here of a duet between a tenor and a bass baritone, from Verdi's Don Carlo
BTW, this example is not a love duet but a duet between old friends.
Ennis would get the deepest voice and Jack the highest one, very well suited for the characters and a male - male love story.
The romantic character, Jack, would be sung by a tenor.
The denying tortured (and traumatized) character, Ennis would be sung by a bass baritone.
It all fits with opera conventions.
And on this, end of