There are levels between Miku, Nino and Ichika.
Ichika stands on a low ground, she wants to win using underhanded methods, removing the competition is easier than making fuutarou fall for her.
Nino wants him to fall for her as she is, she stands on normal level, it's really just about her, not about fuutarou.
Miku wants to better herself into someone fuutarou will fall for, out of those, she has the high ground. Despite Miku's best efforts there's not enough communication with Fuutarou for that to overtake Itsuki.