Hi again,Brokeplex¡
I agree with you that Ennis doesn´t admit his love for Jack until he discovered he shirts in Twist home,but,don´t you think that this moment was the end of a long journey of self-discovering?A journey that perhaps began with the conversation with Cassie who,in some way,taught him what real love was.
I think he was very shocked at the end of their BBM summer because for a few weeks in his life,he felt loved and with someone who cared for him,-we must not forget that both of them were some uprooted boys...-.But at the same time,he knew he must put himself face to face with the real life,that one that doesn´t allow guys like them,he must keep on being a "real" man...And his affair with Jack and,above all,what he felt for him,were an important obstacle to get it,´cause it had changed all his world,his life and his rules.I think Ennis,in some way,loved and hated Jack and himself for this changes.
Regarding to when I realised they were falling in love,I think that in the scene when Ennis speaks "more than in a year"they seem to be already quite smitten,IMO.