I do think that there is a certain kind of love from Faye for Bubbles, I just don't think its romantic.
I don't know how many people have ready CS Lewis' book "The Four Loves", but there's one he discusses called "Philia", the friend bond, when one sees another as close to them as a sibling. Its the one that develops between two people with similar interests, values or in the case of Bubbles and Faye, similar pasts. Both had to deal with extremely traumatic events in their respective pasts; Faye's father committing suicide, Bubbles' team getting killed. Both tried to get away from those events that eventually affected them (Faye's alcoholism, Bubbles' locking the memories and accidental loss of said memories). Both hit rock bottom, but while Faye had Marten and Dora and Hanners, who did Bubbles have? Corpse Witch, the one who had her in that position in the first place. Faye saw herself in Bubbles and has tried to help her, still trying to help her. And Bubbles has done the same with Faye.
The problem is that Bubbles might be feeling "Eros", Erotic/Romantic love (or what people tend to think of today as "the only kind" of love).
There's certainly love between Bubbles and Faye, but I'm also certain that Faye's love is a different kind to the one Bubbles might feel and certainly different to the one Amanda and Evie have convinced themselves of.