看看這個文件能不能幫你。

https://www.alberta.ca/system/files/jus-general-information-spousal-and-partner-support.pdf

How Long is Spousal Support Payable?

If parties lived together for more than 20 years, or if you add the years of living together to the recipient’s age, and the total is greater than 65, then the support will be paid indefinitely. 

最後一頁有更多信息。