If they are both able to earn their own money, I think they can both continue to gamble. They can also share household expenses. I think there is a possibility that both of them might get out of control, but it is not a sure thing, and both of them can manage to act responsibly. I don't think it's right to have prejudiced thoughts against this imaginary couple. 
Well, I find this very difficult to resolve. We cannot force a person to quit gambling. While we are gambling. If economic conditions are good and both people know how to control themselves in gambling and have a lot of free time. Both could use some time to gamble. If either of the people has an addiction and a difficult economic situation, I think both should quit gambling. We cannot gamble in front of people who are addicted to gambling, and they will not be able to go through rehab.
But unless if we are talking about a moderate gambler who do not gamblers all ways, but if we mean full-time gamblers, then both parties are not suitable to be husband and wife.