You want him to be Jaime 'I not lurve u anymoar Cersi' Lannister but then complain when he doesn't care if she was with another man (if he knows and believes).
Make up your mind. Do you want him to care, which would show he still has feelings for her, or not care?
S6 Jaime makes sense. Every scene of his shows him drifting away from Cersei, doing things the way Cersei wouldn't want him to, having those moments with Brienne, trying to avoid bloodshed etc. Even his initial scene with Cersei (comforting her over Myrcella) is understandable. She's a grieving mother and he's a grieving father of the deceased. He'd have been a cruel dick to scorn her under those circumstances. It'd have been him taking a step backwards on his path to redemption. And that's not what the fans want right? Show Jaime needs more time and incentive to break away from Cersei, as their relationship has not been as simplistic as it's been in the books and show Cersei is not as evil and one-note as her book counterpart, @A spoon of knife and fork made a great case for s6's Jaime here. Generally speaking, it seems that some people who tend to (over)analyse every single paassage in ASOIAF, can't be bothered to scratch beyond the surface of GOT while they watch with one eye closed.
Jaime says one thing and does the other? Wow so like a human tends to do. Fancy that. Characters lie to others ('I love Cersei with all my heart') to reach a goal, are in denial or not yet fully in tune with their feelings? How human of them.
Why is it that people expect characters to be : robotic, infallible, omniscient, truthful (always) stagnant (and then complain about the seeming lack of character growth), always completely aware of what they feel/want, never changing their minds?
That's being one-dimensional and not human-like.
Anyway, it's not regarding Jaime but it's worth reminding that character development doesn't only have to be positive/redemptive. There can be a negative one too. See Mad King, Lady Stoneheart, Sansa or people's expectations for rezzed Jon (less forgiving/noble, ruthless etc) to name a few examples.