I think one of the things that I like about Forest is the way she writes maturation proceeding in fits and starts, and sometimes characters even regress from insights that they've had. I'm mildly surprised that Nicola articulates the sentiment, which does seem to be a Lawrie-ish thing to do--Nicola usually has more social nous about what's acceptable to articulate. I'm not so surprised that the full truth that adults feel things as vividly as teenagers do hasn't quite sunk in for her, and perhaps in this emotionally turbulent situation, rattled by Rose's displays of grief and Chas's innocent but revealing natter she does regress a bit.