Episode 5.5 [Rewatch]

[Naivety]

I've always thought that as Ruth's disappearance had to be top secret, they had to make it look as though it was all real.

When the phone call comes through it does look as though at that point Harry doesn't know that the body is not Ruth. The devastated look on his face seems so real. But then as SilkTie says, it may be because he knows he has to say goodbye to Ruth for ever.

The moment when he sees the body at the morgue, seems fake to us, but for the benefit of the attendant it would look as though he was visibly upset. If the attendant was to be questioned by Mace then he would honestly say that Harry reacted to the sight of 'Ruth' on the slab.