Star Trek: Everything We NOW Know About The Burn

Another in a seemingly endless list of planets to leave the Federation, Betazed, one of the core members in the 24th Century at least, had not only seceded but had erected a psionic barrier around their system. In effect, this barrier served as a physical wall, protecting Betazed while at the same time locking them in an isolated state. 

Generations of Betazoids grew up behind this barrier, yearning to know more of the outside universe. Older members of society remembered the feeling of being left behind by Starfleet and the Federation, leading to further distrust. By 3196, Admiral Charles Vance was fully aware of the harm caused by Starfleet's withdrawal and how that had damaged the Federation's credibility and reputation throughout the quadrant. 

Breaking down that barrier was not simply a case of diplomacy. President Emerin Sadal travelled to Earth with the intention of refusing any petitions for Betazed to rejoin the Federation, believing that an isolated planet was a safer planet. His daughter, Tarima, was a prominent member of the Betazoid Youth Movement and an influential voice in society.

The deep will for younger Betazoids to connect with the rest of the quadrant, along with the Federation's olive branch (positioning the seat of government on Betazed and not Earth), helped to thaw the century-old mistrust. The faith and respect that the Federation displayed went a long way, though the permanent presence of Starfleet vessels in orbit didn't hurt, either.