Shattered Soulmates by Melanie Jaynes

Beta Miles Reid and Marissa Hunt have endured a stormy relationship for over a decade. Marissa, known for her dramatic and restless nature, frequently leaves Miles for months at a time, only to return when she wants. Her unreliability destabilizes their relationship, leaving Miles hurt, confused and insecure.
Recently, 22-year-old schoolteacher Paisley Woods joins the pack, and Miles discovers she is his fated mate. Given Miles’s past relationship trauma, Paisley agrees to wait a year before their bonding ceremony. However, Marissa returns the evening before the ceremony, believing Miles’s hesitation means he still belongs to her.
Marissa’s presence reignites old feelings between them. Miles finds himself slipping back into familiar patterns with her and cheats on Paisley. Conflicted by his affections for both females, Miles must face the repercussions of past mistakes and the reality of whether he can hold on to a love that was never truly his, or save the one that may never be again.

As everyone grapples with the fallout, Marissa continues to create chaos while Paisley delves into the heartbreak of broken trust as she seeks a path forward.