If they are married there is no problem, the law can settle this issue, but since they are not married the law about conjugal properties has no effect here, if the woman is righteous and she loves the man she can share the money or give part of the winnings but it seems the woman don't want to do that so they will likely land in court, I'm sure the court will do an intervention and settle this out of court, its not good if in relationship money is the root of misunderstanding.
There are so many marriages that ended in divorce because of issues about money so it's unlikely they are going to get married if they cannot settle this issue.