Virginia's love for her husband and his trust in her is at stake by hiding what transpired between her and the ghost from her husband by Virginia.
Comment on the relationship between Duke and Virginia in light of this remark.( Chapter 7 )

It can be seen that the relationship between the Duke and Virginia might be at stake because of her secrets. Though the Duke feels that a wife cannot keep secrets from her husband, she makes it clear that she could not reveal what transpired between herself and the ghost saying that she owed the ghost a great deal for showing her what Life meant, and what Death signified, and why Love was stronger than both.

This statement reassures the Duke and he says that she can have her secrets, as long as she loves him unconditionally, and as long as she promises to tell the secret to their children. 

Regards