Section 236 of the Domestic Relations Law was amended in 2016 to provide that retirement is a basis to modify an award of spousal maintenance. The text of the bill can be found here. Critically, voluntary retirement is only a basis to modify spousal maintenance when the award of spousal maintenance was set by a judge after a trial. When parties agree upon an amount of spousal maintenance, the standard for modifying the agreed upon maintenance is a showing of extreme hardship. This change in the law now provides an opportunity to former spouses paying maintenance to come back to court upon their retirement to reduce their financial obligations to their former spouse.
The 2016 amendment had numerous other changes discussed in other posts. Here is an interesting article posted by the New York State Bar Association about the 2016 changes.