if there is one thing that i thought was weak in this show it was the dialogue, especially among the main characters. not the writing itself but the messages/statements that characters say to each other like jon & sansa and now that we're talking about them, jaime & cersei.
cersei says "tommen betrayed us" and that does not alarm Jaime NEARLY as much as it should. the actor just makes a startling face as a shocking reaction, but that's it. he doesn't say anything to be like "cersei? what the fuck you mean our son betrayed us? or is that something you're just telling your crazy ass self?"
right after she said that, jaime should really not feel safe with her. if tommen "betrayed" her, what's to stop cersei from turning her back on jaime if he "betrayed" her?