What does Sebastian's wedding ring symbolize for Lydia in the novel, American Dirt?

Upon Sebastian's death, Lydia retrieves his wedding band from his finger in his memory. In times of trouble, Lydia finds herself slipping her finger into Sebastian's wedding ring as a form of comfort and protection. Each time she invokes this habit, she and Luca seemingly thwart potential danger. At one point she imagines that the ring is "like the magic ring from the Hobbit" and it can make her and Luca invisible (257). Sebastian's ring ultimately represents the strength and fortitude Lydia possesses to get Luca to safety.