Spousal support, or "alimony" is not automatic, even if you have a prenuptial agreement. The court will still examine whether or not it is fair or necessary to award spousal support. Typically the court will consider the health, education, work history and current job prospects for your ex-spouse. If the court finds that there is a severe disparity in relative economic strength, then the court may award support to ensure that divorce does not result in your ex-spouse losing their standard of living.
The court will always look to the health of the spouses. If, for example, if your partner has a serious health problem that precipitated their exit from the workforce, then the court may be more inclined to order support. They may do this because your spouse cannot support him or herself even if they wanted to and the court does not want your divorce to land your ex-spouse into poverty.
Assuming your spouse is sufficiently healthy to work, the court will next examine your spouse's education and work history. Does your spouse possess a resume that, while outdated, may still impress many employers? Essentially, if your spouse gave up early on a promising career or degree then you will be more likely to owe alimony. The more independent your spouse, the less likely that you will owe support.
Finally, the court will dig into your spouse's current employment, assuming he or she is employed. Is this the kind of job that can be parlayed into a better career? Are they able to support themselves? The court will want to know how, if at all, financially capable your spouse is. If you cannot tell, the ongoing theme is whether or not your spouse can financially support him or herself.
If you are considering divorce then you may want to speak to an attorney. You should educate yourself on your potential obligation to pay spousal support. Once the divorce decree and court orders are entered you will be stuck with them, unless you can get a modification. So it is best to gather all the information you need so that you are prepared for any outcome.