inaccessible variants

Imagine you have 3 variants:
Size: M, Color: Blue
Size: M, Color: Green
Size: S, Color: Green

User clicks “S” – he now sees “S” rounded and “Blue” crossed.

Problem: There is no way to change selection to “Blue” any more. It becomes unavailable until user resets the whole selection and starts from the beginning. (And yes – I know what to do, but user is not clever enough…)

I want to achieve this: User clicks on crossed “Blue” and this forces “Blue” selection. Another conflicting attributes are reset and become available for user to select. (So user now sees “M” and “S” both unselected.)

Any way to get this? Any ideas?