https://www.cadivorce.com/california-divorce-guide/spousal-support/how-spousal-support-is-decided-in-california/
Length of Spousal Support
A general rule is that spousal support will last for half the length of a less than 10 years long marriage. However, in longer marriages, the court will not set alimony duration. The burden will be on the party who pays to prove that spousal support is not necessary at some future point in time.
The duration of spousal support is left to the discretion of the court within certain general equitable principals and guidelines most often set forth in common law case histories. In the late 1990s, alimony duration was linked to a transition period from married to single life. The circumstances vary from person to person, but the courts rarely favor “lifetime support.”
One appellate court put it this way:
“As recognized by our Supreme Court, the public policy of this state has progressed from one which entitled some women to lifelong alimony as a condition of the marital contract of support, to one that entitles either spouse to post-dissolution support for only so long as is necessary to become self-supporting.”