The OCFA is the Ontario Cemetery Finding Aid & is a searchable online aid.
Marion Rennie McIntyre is interred in the Kincardine Cemetery in plot 646. There is no mention of her husband on the stone, only that she was the wife of William McIntyre. I believe William had a brother Donald & a sister Nichol.
Marion died April 30, 1877 aged 54 years.
There is no transcription for A William McIntyre in the Kincardine Cemetery.
In the Kincardine Cemetery there are 8 Donald McDonald's buried there.
Do you know when Donald was born ?
The Bruce County Archives in Southampton, Ontario have indexed a lot of obituaries. They might be a big help to you.