Cover art of the first DVD compilation released by King Records, featuring main characters Ryūji Takasu and Taiga Aisaka (Photo credit: Wikipedia)
I had a flash of inspiration on my morning commute yesterday about the ending of Toradora! and why it actually makes sense from a narrative point of view. I jokingly called it "bullshit", but it's really not. See, the problem with Ryuji and Taiga's relationship is that, as Ami said, it did have this weirdly "surrogate father/daughter" vibe to it, and one aspect of that was Taiga's initial total dependency on Ryuji and his mother for even her most basic needs like food and good domestic hygene.
I think Taiga recognized that she had to learn to stand on her own two tiny feet and be her own woman first before she could formally enter into relationship with Ryuji as a full and equal partner. It was a necessary step for her after their relationship took a decidedly romantic turn. It wasn't (obviously) a "Goodbye forever" but a "Goodbye for now, there's something I have to do first."; It was already alluded to that Taiga was slowly learning from Ryuji how to fend for herself, cook for herself, clean up after herself, etc. She also "got over" her longtime "crush" on Kitamura, especially after Kitamura's very public and very embarassing confession to Kano, the Student Council President, who went to America. It's obvious that Kitamura's not giving up on her, as he announced his own intention to study abroad in America the very next year. In other words, he still loves her and is following after her. It's a reality Taiga had to just accept. Minori had a much tougher time because she did in fact still love Ryuji herself but felt in her heart that Ryuji made a better match for Taiga than herself.
Anyway, as I mentioned below, you have to watch through ALL of the credits to get the true and happy end of Toradora! The best things come to those who wait, etc.
I for one believe it leads to this...
and this: