Can they move forward over their differing opinions on children?
On what would have been Peach's due date, Zack receives the good news that his viral load is now undetectable and as he spends time with Whitney at their daughter's tree, Zack suggests they could try for another baby.
But when she reveals that she can never put her body through that again and doesn't want to try for another baby, Zack is left heartbroken. And as they have a difficult conversation about their future and children, will they manage to move forward?
On Chelsea's advice to keep talking to Zack so that they don't lose each other, Whitney speaks to him, but it's clear that Zack thinks they're too far apart on this issue.
And after finding Whitney in tears, Sharon later confronts Zack.
EastEnders continues Mondays to Thursdays at 7.30pm on BBC One