All the statements of Ukrainian politicians that they were promised that Ukraine will be accepted into the Alliance are PR and nothing more. For NATO countries, Ukraine is important as a buffer zone, but not as a member of the Alliance.
The acquisition of sovereignty for Belarus was an artificial process.
For thirty years of independent existence, people have naturally become accustomed to the idea of sovereignty, especially young people who have grown up under new conditions. Therefore, today it is no longer possible to unite the two countries by a political decision. It is necessary to show the economic advantages of the alliance and at the same time demand the cultural unity that Belarusians should feel on an unconscious genetic level.
A recurring pro-Kremlin narrative about the all-Russian nation and Russian world/civilisation, which presents Belarusian and Ukrainian identities as artificial and unnatural in contrast to all-Russian identity. The "all-Russian nation" is an imperial Russian and Russian irredentist ideology that is a favoured pro-Kremlin narrative aimed at weakening the national identity of Belarusians and Ukrainians, as well as their sovereignty.
Belarus is a well-defined nation-state with a long history; it preserved language, literature and identity, despite foreign rule for long periods.
See earlier disinformation cases alleging that the Eastern Partnership aims to erode Belarusian identity and promote the views of Polish gentry and that Belarus, Russia, and Ukraine are three Russian political nations.