He will never be able to give it directly to her so he'll find a way to slip it in her bag but forget to add any kind of note to prevent her that it's "the guy who sits next to her every morning".
by the way, what did he buy her? We know it's neither make-up, sweets or accesory since we were shown him thinking about it. From the size it has in penultimate page, it looks like chocolate to me. I hope he'll give it to her soon if that's this or it will melt...
Edit: I'm dumb I did not even pay attention to the pages just before. It was in the flowers/vase section, there seemed to be some kind of small frame and that's the only thing that seems to fit that size of package.