The two occasions that Ennis goes to his knees he is leaving Jack. The first time as Jack leaves after their time on BBM, and he regrets having to lose Jack, but is left with the only solution that he feels he can make. Again, he falls to his knees, embraced by Jack,when they have, we find out later, reached the conclusion of their love story. In both Ennis gives in to what he has held in check and it has a huge impact. Why do we feel it's impact in our lives?