I don't even like Tiffany, but I'll give you props for a very thorough and well-constructed rant.

I like her much more than the migraine inducing Sasha and Gigi though, and agree that she, like most every other girl in the game, deserves some choices on how their romance should go. Personally, I'd rather have the option to ignore her over abusing her.
To be fair, the whole rivalry of MC and Tiffany is absurd to begin with, stemmed from the failed prank on Camilla, orchestrated by Tiffany herself, and even seen through by Camilla, thus liberating the MC of the accusation of him being the one who thought of the prank, furthermore, the way MC is so deadass pathetic, and outright stupid on some occasions is just... meh.
Is good that there are characters with real life struggles, like Lira, or Umiko, but indeed, there are some characters that are quite frankly, annoying, like Sasha with her
clown-like attitude, or Gigi, with her
hard ro get demeanor
.... anyways...
The game has its good points, however, the MC should be less pathetic and more assertive, the MC has its moments of brilliance, where it feels very humane, empathetic and caring, whereas there are parts that are idiotic and simply breaks the character into an absurd simp that only wants to get laid, period.