"Do not marry till you are able to support a wife." Sounds pretty valid to me. It doesn't specify whether you're male or female (or other), and doesn't specify

"Do not marry till you are able to support a wife." Sounds pretty valid to me. It doesn't specify whether you're male or female (or other), and doesn't specify that you will have a wife to support; only that you shouldn't marry until you are able to support a wife. Maybe you'll have a wife, maybe you'll have a husband, maybe you'll reject those terms or find them inapplicable. Whatever term you use, if you could support a wife, you could support your <other>.