Do you really think she killed herself because he wouldn’t marry her? Remember, Jagger is the guy who went through a marriage to his last consort in Indonesia, then claimed later that it was intentionally invalid. She had about as much chance of marrying him as she had of marrying Liberace. And she wasn’t a new babe in the woods when she took up with him. Most likely she was bipolar or had a condition like that.
Obviously there were many factors, as I implied at the beginning by saying "contributory", not "absolute", and "faithfulness", not "marriage."
Could be bipolar, but there are a lot of women who still think that they will be the one to change the man.