Based on the search results, it appears that there are multiple instances where the Boston Bruins were defeated in the Division Finals. Here are a few examples:
It's worth noting that the Bruins have a long-standing rivalry with the Montreal Canadiens, and the two teams have played each other in numerous playoff series over the years.
If you're looking for a specific instance or year where the Bruins were defeated in the Division Finals, please let me know and I can try to provide more information.