DT must suspect Claire, and hasn't been protecting her all this time, but rather keeping her where he can see her, and hoping she'll trip up and implicate herself.
That's why he let them meet, so he could film it and see what they said, and why he is now distraught they have legged it - not for her safety (if he truly believed that he wouldn't have left them alone, even with cameras) but because now they have both disappeared, and he has lost not one, but two suspects.
I also think everyone is being too harsh on Ellie. She has lost everything - her life, her job, even her son - because of something her husband did. I can see why Beth would be furious that Ellie's actions in hitting Joe have made the confession inadmissible - Beth would assume that as a police officer Ellie would know that, and should have acted professionally rather than as joe's wife - and I can also see that, quite obviously, the friendship would change and not survive Danny being killed. But the level of hatred and vitriol towards her, seemingly from the whole community, when she did nothing wrong, and didn't deliberately mishandle the case, or destroy evidence etc is just wrong.