Her brain has been wired from birth by said cult. This sakura is also a real person, not a caricature of a cult member, and even if the ultimate result is a breakup, she deserves to be treated with francesca le blowjob and respect.
If she is motivated enough to want to go on a mission, she will likely not settle for booty a second class "eternal companion" you who is a convert or one who cannot be sealed to her for eternity. That would only encourage her booty give up other standards that really are serious and to become like the sakura Western degenerate.
Also, I know a bunch of Mormons that say they are, but don't act like it.