Idk man. I've had a lot of female friends and I can say, just because she may treat you differently or be very close with you, it doesn't mean she wants a relationship with you. Unless I'm also dense af but I'm very sure of it, since I have heard one said so.
Honestly it would be refreshing if the mc actually ends up getting close with another character, make the fmc realize her feelings and regrets for friendzoning him.
Like it happens a lot in manga. Mc that is dense or avoiding catching feelings, and an fmc that doesn't really know her own feelings and keeps friendzoning the mc. But this always ends simply even with the drama. I feel like the girl usually never get the repercussions of her actions because the mc would always definitely go for her even after all that's said and done to him.