There was no such thing as 2008 Bucharest Memorandum, you are probably confusing it with the 1994 Budapest Memorandum. But NATO did hold a summit in Bucharest in 2008. Ukraine and Georgia hoped to get invitations to join NATO. Under Russian pressure, they were denied entry, and that was the end of it. This left Georgia and Ukraine outside NATO's protective umbrella and enabled Russia to invade both without triggering a response from the entire alliance.

The "eventually" you are referring to was nothing more than a polite "no", issued in the final statement of the summit as a consolation (one day we will invite you), after allies had made their negative decision.