Casualty star Tristan Gemmill reveals how his on-screen marriage ends (BBC1, Saturday, Feb 6)…

How have Adam and Jessica been coping with Harry’s death since the funeral?
“Not great as you might imagine. Adam is trying to make sure Jessica is all right, but he’s so busy worrying it’s stopping him from grieving. And Jessica is unable to deal with Adam because seeing him reminds her of her baby.”

Does she blame him for Harry’s death?
“She feels irrational anger towards him because she wishes he’d saved Harry and not her. But in reality he couldn’t save Harry because he couldn’t see him in the water. They’re both in a really bad way at the moment. They’ve become so tense and awkward with each other you could cut the air between them with a knife.”

Why have they both returned to work so soon after the burial?
“It’s partly denial and it’s also mildly distracting from their grief to have something to occupy their minds. But it’s only a short-term solution because it stops them grieving properly.”

What is the deciding factor for Jessica to end her relationship with Adam?
“At work she bumps into her old best friend Linda. Linda is pregnant and planning to move to America and she makes an almost flippant remark that Jessica should come with her – and Jessica says that she will.

So this is a snap decision in some ways?
“It is. People in grief and crisis don’t always behave rationally and Jessica makes a snap decision. Adam’s really got nothing to do with it – he’s left in the dark about the whole thing. Jessica knows they can’t carry on the way things are, but she doesn’t sit down and discuss it with him.”

Why America?
“When Linda and Jessica were training to be nurses they had this fantasy of going to America together. But they went their separate ways after Jessica married Sean.”

How does Adam take the news when she breaks it to him?
“It doesn’t come as a surprise to him. He’s upset, but knows they can’t come to terms with Harry’s death and have both gone into their own worlds. Adam has known he’s been losing her for a while. He tried to pretend everything was fine but he knew it was false. It was really only ever going to result in Jessica leaving, unfortunately…”