Every marriage is different, and every life is different within each marriage. The roles of each spouse in marriage are also different. In some marriages, both spouses work and earn close to the same income, while in other marriages one spouse is the main "breadwinner" and the other spouse has other roles, such as caring for the children and other tasks and responsibilities. Following a divorce, these roles obviously change.
While one spouse may have abandoned a career to take care of the family, that spouse may be left at a severe disadvantage when the previous income earned by the other spouse is no longer available. Furthermore, with a constantly changing and evolving economy, a spouse's previous role in the workforce may have changed completely or even become obsolete. In the United States, the courts understand that each marriage and divorce is different, and that some spouses may find it difficult to re-enter the workforce after a long time away.
Spousal support, or alimony, is one way to help a spouse maintain a reasonable or similar standard of living following a divorce. The courts will look at the earning, or lack of earning, by each spouse, as well the standard of living of the couple while in the marriage to make a determination as to how much spousal support should be awarded.
Other factors that will also be taken under consideration include the age, financial condition and emotional state of each spouse, the length of the marriage and even the time it would take for a spouse to get the education or training to re-enter the workforce and become self-sufficient.
Source: findlaw.com, "Spousal Support (Alimony) Basics," Accessed on Jan. 9, 2017