diff --git a/core/invitation/service.go b/core/invitation/service.go
index 936f0c620..c3dafcdb5 100644
--- a/core/invitation/service.go
+++ b/core/invitation/service.go
@@ -247,12 +247,15 @@ func (s Service) createRelations(ctx context.Context, invitationID uuid.UUID, or
 }
 
 func (s Service) Delete(ctx context.Context, id uuid.UUID) error {
+	// Remove every relation anchored on the invitation object, not just the org
+	// one. createRelations writes both a user (app/invitation:<id>#user) and an
+	// org (app/invitation:<id>#org) tuple; filtering by org alone leaked the user
+	// tuple on every accept/expire/delete. Omitting RelationName matches both.
 	err := s.relationService.Delete(ctx, relation.Relation{
 		Object: relation.Object{
 			ID:        id.String(),
 			Namespace: schema.InvitationNamespace,
 		},
-		RelationName: schema.OrganizationRelationName,
 	})
 	if err != nil {
 		return fmt.Errorf("failed to delete relation for invitation: %w", err)
diff --git a/test/e2e/regression/api_test.go b/test/e2e/regression/api_test.go
index eca5df037..f45e7ca8c 100644
--- a/test/e2e/regression/api_test.go
+++ b/test/e2e/regression/api_test.go
@@ -2319,6 +2319,14 @@ func (s *APIRegressionTestSuite) TestInvitationAPI() {
 		}))
 		s.Assert().Error(err)
 
+		// no SpiceDB relation should linger on the invitation object after accept:
+		// both the #user and #org tuples must be gone, not just #org (gap #1661.3)
+		leftoverInviteRelations, err := s.testBench.AdminClient.ListRelations(ctxOrgAdminAuth, connect.NewRequest(&frontierv1beta1.ListRelationsRequest{
+			Object: schema.JoinNamespaceAndResourceID(schema.InvitationNamespace, createdInvite.GetId()),
+		}))
+		s.Assert().NoError(err)
+		s.Assert().Empty(leftoverInviteRelations.Msg.GetRelations())
+
 		// should be part of group
 		listGroupUsersAfterAccept, err := s.testBench.Client.ListGroupUsers(ctxOrgAdminAuth, connect.NewRequest(&frontierv1beta1.ListGroupUsersRequest{
 			Id:    createGroupResp.Msg.GetGroup().GetId(),