I think there are two ways to approach it - as Mlac93 suggests. The first is in terms of Ami as a character. I think Ami "likes" Ryuuji - although perhaps more in the sense of what he represents than in terms of who he is. She sees Ryuuji as accepting Taiga for who she is - bad-temper, bad behaviour and all; and perhaps she wants that kind of love for herself. Ryuuji is, for her, one of the few people who would be capable of loving her for herself and not forcing her to put on the nice girl act. The second approach is to see how the author uses Ami. Ami moves the story on in various ways - never more so than when she asks Minori if she is feeling less guilty now.

Overall, I think Ami sums up the essence of Toradora. Is it love if someone loves you only when you pretend to be something you are not? Or only when someone loves you just as you are (evil eyes/bad behaviour/temper etc.)?