The citizen spouse must sign a contract (I-864) with the Federal government promising to support the non-citizen spouse financially. In most cases, even if the couple divorces, the citizen spouse must continue to support the non-citizen spouse.
The person asking for alimony must show the court that he or she needs financial support, and that the other spouse has the ability to provide financial support.
As with marriage, divorce has zero impact on whether a person who is in the nation illegally can be removed from the country. If you are in the US illegally, getting married even to a US citizen won't grant you legal status nor does it make you eligible for legal status. With divorce your circumstances don't change.
Someone doesn't have to be a US citizen. The qualifications to draw a spouse benefit in that scenario is age at least 62, have a spouse who draws SS and have been in the US LEGALLY for at least five years.
You need to consult a family law attorney in your state familiar with divorcing someone who is outside the country. Most states will allow a divorce if one of the parties is a resident (usually met after living in the state for 6 months or more).
Typically, this obligation continues until your spouse becomes a U.S. citizen, accrues 40 qualifying work quarters in the U.S. (roughly 10 years), permanently departs the country, or passes away.
Even if a spouse immigrant is denied alimony in divorce proceeding, she or he can seek support as set out under form I-864. Further, the spouse immigrant has no obligation to find a job (which is a requirement for alimony in California) to obtain support under form I-864.
Generally, women suffer more financially than do men from divorce.
In the USA, yes, you can file for divorce without the approval of the other person.