After how many issues of a side character getting romantic play do you add the Harem tag? Because I'd consider adding a "Harem" Theme Tag (IE. Multiple love interests) at this point, she's gotten dozens of panels and issues dedicated to her, and even though she won't win because of the "Main Girl Has Her Name in the Title" syndrome, it still makes reader have to think, where is this even going?
It happened to Kawaii 'Kouhai ni Iwasaretai' recently too, if you keep having side characters constantly flirting with the MC, they eventually get upgraded to love interest.