Periodic payments can last for a shorter, a longer, or an indefinite time.
Marriage was seen as being contracted for on the basis of a life-long union of a man and woman. Contrary to what most of us in North American culture now think, marriage is no longer for life. Since 1968 in Canada, any marriage can be ended, abruptly, at any time, at the wish of one party, without consent of the other. In the search for a foundation to replace the old foundation, many different theories of spousal support were put forward. In fighting a lawsuit, you chose the theory that supported the best award for your client.