I think that this scene dislikes not only for seeing Jack so disappointed and sad,but because it's a proof of both selfishness.Yes,Jack was very generous by driving so many hours for being with the man he loved; that's a generosity's act,because he didn't think in himself,in the troubles and tiredness that this could bring to him...But,at the same time,he was shellfish because he took for granted that Ennis would run to him immediately,no matter his situation,no matter even if this was Jack's wishes,not necessarily Ennis in that moment.
And Ennis...well,Ennis was shellfish and,IMO,stupid,because he didn't realise the effort his friend had done to be with him; no matter what they decided after,at least Jack had the right of spending some time by his side.And I bet he didn't either think about what the news meant for Jack and that he was,somehow,obliged to look for a solution,and think a little more in Jack and not so much in himself and his fears.JMHO.