public IReadOnlyList<Row> GetRowsRelatedToOriginRows( 
   IEnumerable<long> originObjectIDs
)

public async Task GettingRowsRelatedByRelationshipClass()
{
    await ArcGIS.Desktop.Framework.Threading.Tasks.QueuedTask.Run(() =>
    {
        using (Geodatabase geodatabase = new Geodatabase(new DatabaseConnectionFile(new Uri("path\\to\\sde\\file"))))
        using (RelationshipClass relationshipClass = geodatabase.OpenDataset<RelationshipClass>("LocalGovernment.GDB.luCodeViolationHasInspections"))
        using (FeatureClass violationsFeatureClass = geodatabase.OpenDataset<FeatureClass>("LocalGovernment.GDB.luCodeViolation"))
        using (Table inspectionTable = geodatabase.OpenDataset<Table>("LocalGovernment.GDB.luCodeInspection"))
        {
            List<Row> jeffersonAveViolations = new List<Row>();
            QueryFilter queryFilter = new QueryFilter { WhereClause = "LOCDESC LIKE '%Jefferson%'" };

            using (RowCursor rowCursor = violationsFeatureClass.Search(queryFilter, false))
            {
                while (rowCursor.MoveNext())
                {
                    jeffersonAveViolations.Add(rowCursor.Current);
                }
            }

            IReadOnlyList<Row> relatedOriginRows = null;
            IReadOnlyList<Row> relatedDestinationRows = null;

            try
            {
                QueryFilter filter = new QueryFilter { WhereClause = "ACTION = '1st Notice'" };

                using (Selection selection = inspectionTable.Select(filter, SelectionType.ObjectID, SelectionOption.Normal))
                {
                    relatedOriginRows = relationshipClass.GetRowsRelatedToDestinationRows(selection.GetObjectIDs());
                }

                bool containsJeffersonAve = relatedOriginRows.Any(row => Convert.ToString(row["LOCDESC"]).Contains("Jefferson"));

                List<long> jeffersonAveViolationObjectIds = jeffersonAveViolations.Select(row => row.GetObjectID()).ToList();

                relatedDestinationRows = relationshipClass.GetRowsRelatedToOriginRows(jeffersonAveViolationObjectIds);
                bool hasFirstNoticeInspections = relatedDestinationRows.Any(row => Convert.ToString(row["ACTION"]).Contains("1st Notice"));
            }
            finally
            {
                Dispose(jeffersonAveViolations);
                Dispose(relatedOriginRows);
                Dispose(relatedDestinationRows);
            }
        }
    });
}

private static void Dispose(IEnumerable<Row> rows)
{
    foreach (Row row in rows)
        row.Dispose();
}

public async Task DeletingARelationship()
{
    await ArcGIS.Desktop.Framework.Threading.Tasks.QueuedTask.Run(() =>
    {
        using (Geodatabase geodatabase = new Geodatabase(new DatabaseConnectionFile(new Uri("path\\to\\sde\\file"))))
        using (RelationshipClass relationshipClass = geodatabase.OpenDataset<RelationshipClass>("LocalGovernment.GDB.luCodeViolationHasInspections"))
        using (FeatureClass violationsFeatureClass = geodatabase.OpenDataset<FeatureClass>("LocalGovernment.GDB.luCodeViolation"))
        {
            QueryFilter queryFilter = new QueryFilter { WhereClause = "LOCDESC LIKE '%Jefferson%'" };

            using (RowCursor rowCursor = violationsFeatureClass.Search(queryFilter, false))
            {
                if (!rowCursor.MoveNext())
                    return;

                using (Row jeffersonAveViolation = rowCursor.Current)
                {
                    IReadOnlyList<Row> relatedDestinationRows = relationshipClass.GetRowsRelatedToOriginRows(new List<long> { jeffersonAveViolation.GetObjectID() });

                    try
                    {
                        EditOperation editOperation = new EditOperation();
                        editOperation.Callback(context =>
                  {
                      foreach (Row relatedDestinationRow in relatedDestinationRows)
                      {
                          try
                          {
                              relationshipClass.DeleteRelationship(jeffersonAveViolation, relatedDestinationRow);
                          }
                          catch (GeodatabaseRelationshipClassException exception)
                          {
                              Console.WriteLine(exception);
                          }
                      }
                  }, relationshipClass);

                        bool editResult = editOperation.Execute();
                    }
                    finally
                    {
                        foreach (Row row in relatedDestinationRows)
                            row.Dispose();
                    }
                }
            }
        }
    });
}