I have read reports in Al Kafi that seem to point to Imam Hasan being a man that married and divorced many women during his life. Are these reports authentic? What is the mainstream Shia opinion on the marriages and divorces of Imam Hasan

The mainstream shia position is totally opposite what is mentioned above. The tradition above is not authentic. It’s often propagated by the enemies of Ahlul bait.
You will note that we as shia don’t claim all our books are authentic. Therefore some of the Hadith has to be scrutinised