Daughters of the Mayflower Universe by Celie wells

In a tidy world on the brink of destruction, where fate is chosen for you and secrets lurk beneath the surface, fifteen-year-old Karine Lancer discovers her destiny at her grandparents' life celebration-a socially expected but sinister event cloaked in elegance. The clock is ticking as she is unexpectedly betrothed to Jason Fuller, lifelong friend and scion of a powerful industrial dynasty, unveiling a chilling family secret: a comet hurtling towards Earth, with only months left.

Snatched from society's clutches by the outlawed Reds, dwellers of hidden canyons beneath the unforgiving Pacific seabed, Karine finds herself torn between her loyalty and a reality she never imagined. As she fights to be sent home and navigates treacherous landscapes, she carries with her a stolen truth, a ring of significance, and the weight of what may have been.

With ships being readied for escape and time slipping away, Karine must forge her own path amidst deception and danger. The stark truth remains: survival is not guaranteed-it must be seized. Welcome to a world where alliances are tested, choices have consequences, and the comet's ominous countdown looms large. The clock is running. Will Karine outrun fate?