I really think that Aslan's line about no need to talk of the past is incredibly significant. Would they have discussed how she seduced/tricked him with the Turkish Delight and the promise of being King? I'm thinking, no. I don't think they would discuss the nature of the betrayal, I don't think they would know it. And yes, the Witch talks about him being a traitor and such but that is the army and how much would they want to keep thinking of Edmund as traitor when he breaks her wand and almost dies? Where I"m going with this (obviously) is that Edmund's head, during the Lone Islands departure, is very much on Seth Stanleh and family betrayals, and meting out a just punishment. Tender and loving farewells, not so much.