Already have a child and don't want any more kids

Our psychotherapist says: 
It struck me that Natalie keeps repeating how much she loves her son. Maybe in her subconscious, her son remains linked to the failure of her first marriage. When she says her new husband is accepting of her situation, she's actually saying he's managed to accept a child who was potentially the cause of that break-up. Until she hasn't thought this through properly, she'll never be able to build anything solid with her new husband - baby or no baby.    

Our sociologist says: 
This is a huge issue in modern sociey. Where does a child from a previous relationship belong in a new relationship? Where would another child fit into this set-up? Many parents who remarry ask themselves: do we have to have our own child together to make this new relationship valid?