Hopefully Nikki or Cara, but i think it will be Alexis or Lakeyn.
If Nyx would be truly evil, she could make Nikki/Cara decide to move in with MC. This would make MC's life a hell and the other girls furious.
However, most probably that would be Lakeyn.
From the sentence I feel that could be someone close to MC's age.
Otherwise I would also think of Adriana and Mr. Navarro.
Despite the resemblance, I think our MC still does not suspect him to be Santi, and as single-minded as ever, MC can tell him his life story .. again (no high-mile club this time).
The whole conversation could end up in a nice dinner invitation to the Navarros, just to embarrass Gabi again.
I apologize, I fantasize too much. (I must write a lot to overcome my PTSD after playing Acting Lessons last weekend.)