I've always felt people cancel Yotsuba out of the equation under the pretense of "she isn't romantically interested." Why sure, you have to be like Miku, puffing your cheeks so cutely to be "in the race"?
A lot of romcoms make romantic interests rather obvious, but other heroines like Yotsuba can always be someone who is interested, but the author does not choose to dive too much into their internal thoughts to show such. We already know Negi is playing around tropes, but ultimately outdoing them, so I recommend to people who mark Yotsuba on the "friend" or "not like romance" list to toss that away. Yes, keep cheering for the girl you think is going to win, but it's rather disappointing to see individuals who mark a heroine out of the race under a very naive "she isn't trying to be intimate."