Maintenance can be modified prospectively if there is a substantial and continuing change that makes the terms unfair, unless the parties agreed otherwise in writing. Unless a decree or agreement clearly states otherwise, future maintenance obligations terminate upon the death of either party or the recipient’s remarriage. Courts enforce these default rules while honoring lawful non-modifiable agreements. Any modification applies only to installments due after the motion is filed. Parties should draft separation agreements carefully if they intend different outcomes. Colorado statutes and recent appellate materials explain these principles.