The Verdict: Unlikely
Marriage gives no South African status while you live abroad, so citizenship this way is a long shot unless you move. If you have children, check Citizenship by Descent: a child of a South African parent is a citizen wherever born.
Every route for spouses runs through permanent residence and then years of ordinary residence in South Africa itself. There is no consular route and no shortened path for a spouse who stays abroad, and time lived abroad together does not count.
You can apply for permanent residence as a spouse after five years of the relationship, from outside the country. But it then has to be used: it can be withdrawn after more than three years' absence.
If moving is on the table, this answer improves, and the years of relationship you already have count towards the permanent residence application.