Yes, and I think it is the nature of great art that it captures the essence of the human condition, and giving us BOTH this way AND that way, because truth includes BOTH, and not necessarily one OR the other.
"Jack, I wish you knew..." says so much about the anguish and regret from Ennis...the driving force that is in the heart of his grief.
"Jack, I swear I will never..." also says so much about the potential and possibilities from Ennis...the determination to never make the same mistake, hiding his love for another, and to always hold Jack in memory, to keep faith with his one and only love.
What we see is often one side of the coin, and seeing both sides gives us a more complete picture.