I suppose the only solution to this* is patching the exploit/bug that makes the player able to adopt an "unlimited" (maybe it only gets up to 14 which is house limit, but IDK) amount of adults when tapping on "new generation" with no descendants**.
* (Since it the "2 adult limit" seems to be a core feature of the game)
** (I mean it should only let the player adopt once so that the couple may be restored, instead of letting the player adopt multiple adults like what happened to me)