I am sure that her husband is at least half the problem. My dad told me not long ago that they had borrowed money and right after that they and my father were at a family function and her husband was buying drinks for everyone. My dad said he thought, "big spender with my money."
Maybe her husband is mostly the problem, I can't say since no one knows what really goes on in a marriage. She certainly wasn't raised that way.
I wonder if she knows that inheritance is not community property, even in a divorce, unless the money has been put into a joint account and co-mingled with joint assets. My other sister is married and she knew that, put the money into an account in her name only which is just what her husband said she should do because it is hers to do with as she wishes, not theirs. But her husband is a great guy too.