Thanks for your patience.
If the agreement was not incorporated into the divorce decree, then the relevant statute of limitations would be 6 years:
Section 2. Actions of contract, other than those to recover for personal injuries, founded upon contracts or liabilities, express or implied, except actions limited by section one or actions upon judgments or decrees of courts of record of the United States or of this or of any other state of the United States, shall, except as otherwise provided, be commenced only within six years next after the cause of action accrues. - accessible here: https://malegislature.gov/Laws/GeneralLaws/PartIII/TitleV/Chapter260/Section2
However, if the contract/agreement was incorporated into the judgment, then there is no applicable statute of limitations, because statute of limitations do not apply to judgments, as stated in the above code.
There is a different legal theory established in common law - laches:
Laches is defined as an unreasonable delay in making an assertion or claim, such as asserting a right, claiming a privilege, or making an application for redress, which may result in refusal.
The idea is based on equitable considerations- what is fair.
If a party sits on an action so that the other party (and other reasonable persons) would expect that, due to the delay in time, the party has no intent to enforce the agreement, and that enforcement would in fact be inequitable because of that exact time delay- then the court may deny the clalim.
So if a party stops paying on an obligation over 10 years ago, most courts would be compelled that it is inequitable to enforce the agreement/decree at this late date.
Also contempt requires a knowing and willful violation of a court order; if a party is unable to comply with the terms of the order, they will not be held in contempt because that does not satisfy the willful requirement - therefore inability to pay precludes a finding of contempt.