But when you've lost someone close to you, can can go a bit.. numb. I'm a cuddle monster but hated showing signs of affection when I lost close relatives. You can go a bit "in" on yourself so it might be that.
Also I don't think she's someone who plays up for the camera... maybe we just aren't used to seeing a "normal" relationship on screen!
Maybe he is conscious that if he is all over her people will think it is fake? I know this is Peter Andre we are talking about, but I'm tying to think of a reason. My partner and I are very affectionate but I can't imagine being a total cuddle monster when being filmed.