So far this is reminding me of Rebecca by Daphne Du Maurier. The novel is similarly titled after the person the MC is obsessed with and even though, unlike Rebecca, Mayra is alive, she is as overbearing and absolute of a presence in Ingrid's life, even when she's not present, as Rebecca is on the life of the novel's unnamed MC.

I also feel like Ingrid isn't seeing Mayra clearly: she can't help but see a distorted image of who Mayra really is (or has become). Her feelings for and about Mayra are so strong that she cannot see past them. Mayra seems to be struggling in some way, yet Ingrid seems incapable of getting rid of her "idealised" image of Mayra. She can only see Mayra through the effects her friendship had on her life and her own self-image and through her teenage feelings of inferiority, admiration and envy. Just like in Rebecca, the MC of this story seems to be dealing with a ghost she's made up in her mind rather than with a real person.

As a side note, even though I found Rebecca more atmospheric than Mayra, there are also some similarities in the setting: the old house, big and looming and kind of its own entity; the nature surrounding it, which also acts as an extension of the title character's influence. I wouldn't be surprised if Nicky Gonzalez was inspired by Du Maurie's novel.