Deleting relationship between users with rules

I can't find any info on this.

My scenario:
-- Whenever two users get into a relationship, a node is created, referencing both users (with entity reference module).
-- Both users are able to edit this node.
-- The node contains two dropdown cck fields called 'A' and 'B' with "yes" or "No" options.
-- User1 is instructed to only answer field A and user2 field B.
-- If either answers "No", I want the relationship to end.
-- If no response by either after a certain period, I want relationship to end.

Rules:
-- I created a rule on the event of content being updated
-- Checked for the value of field A or B is "No" using Data comparison.
-- I then used the "Delete, cancel or disapprove relationships between users" Action and used the user referenced fields for the Requester and Requestee Data selector option.

But nothing happens when the node form is updated and a user selects "No". The relationship between the two remains.

How can I do do this properly? Thanks.