This new girl addition makes no sense, it's clearly stated that mc has no one on his side, helping him until fmc came, but what this new girl trying to show proves that statement wrong.
So the situation comes to either:
A. The new girl is on mc side and has "tried" helping him but not significant enough that mc can consider her being on his side. => which makes both mc and her look bad.
Or
B. The new girl just implies that she's on his side and has done fuck all in term of actual action to prove it so mc, being the dense mf he is, doesn't recognise her as being on his side. =>which makes her looks bad.