Fae Gods by Kathy Haan

When Jocelyn’s unhappy marriage hits rock bottom, three strangers appear, offering to help repair her relationship and become the Marriage Doctors. To fully immerse themselves in their role, they move in with Jocelyn and her husband, using their otherworldly understanding of love and relationships to teach him how to care for his wife.
But little does Jocelyn know, these mysterious men have been with her every step of the way, rotating in shifts to watch over her 24/7/365 since the moment she took her first breath. Invisible to her, they have been present for every key moment in her life, their duty to protect her and keep her safe as she is of royal fae blood.
As they work to save her marriage, the fae gods find themselves falling for Jocelyn and she for them. However, their love is impossible and their relationship could have deadly consequences in the fae world. As they struggle to keep their true identities hidden and navigate their forbidden love, they must also confront the dangers that threaten their relationship and decide where their loyalties lie — with the fae world or with the woman they have come to love.