Hey, ya! Use recursion!

AFTER.rb

  # Split long `address_line` line into array of lines
  # each with length not greater than `max_length`
  def divide_address(address_line, max_length)
    assert max_length > 0, "max_length should be a positive number"
    address_line = address_line.strip
    if address_line.length <= max_length
      return [address_line]
    else
      head = address_line.truncate(max_length, separator: " ", omission: "")
      tail = address_line[head.length..-1]
      rest = divide_address(tail, max_length)
      return [head].concat(rest)
    end
  end

BEFORE.rb

  def divide_address(address_line, line_length)
    line_1 = truncate(address_line, length: line_length, separator: ' ', omission: '')
    tail = address_line[line_1.length, line_length * 2]
    line_2 = truncate(tail, length: line_length, separator: ' ', omission: '')
    tail = tail[line_2.length, line_length]
    line_3 = truncate(tail, length: line_length, separator: ' ', omission: '')

    [line_1, line_2, line_3]
  end