It seems strange that there would be no two seats together, and yet the AF line suggests that you may, in the future, find two open seats together - how close are we to your departure date?

Anyway, even if you can not change seats between now and check-in opening, you should have at least one more attempt when online check-in opens. And if two seats are not available together in your cabin, then a quick word with the onboard FAs - as a polite request, not as a demand - should help in locating someone who would be prepared to swap seats with one of you so that you can both sit together - particularly if they can trade a less attractive (e.g. middle seat) seat for a better one.