What if the things she wanted to buy for herself are actually the ones she would buy with Kyouko in mind? But subconsciously? She just doesn't want to admit it. This stuff happens when you put someone on a pedestal and your insecurity reigns. Still, it seems their relationship was never official, pretty vague. Anyway, am staying here for the drama
I think it really seemed for herself, bc of how each gift happened so coincidentally (she didn't just hand them to her iirc, she made Kyouko try them on or held them up to her and stuff). She didn't know if they suited her or not before she tried them either (apparently she just buys shit without checking first, idgi but she calls them impulse purchases), and she didn't know they would suit Kyouko either until she made her try.
The last gift especially, the lipstick is the best example bc she wasn't even the one to pick it out this time. I think the last gift was also the one that hurt the most (besides being the straw that broke the camel's back), bc not only did the bf pick it, not only did she actually think it looked great this time, but because Kyouko reached out and "took" it for herself, when she tried it on. It wasn't intentional on Kyouko's part (i think), but it happened to fit Nacchan's perception of "you take everything that is mine, I have nothing".
Unless I missed something (like how Kyouko feeling lonely and neglected for a while might've have contributed to it, that maybe she wanted to connect to Nacchan again), I think that was probably a coincidence, that this time she took one of Nacchan's items and tried it on without Nacchan being the one to offer it. Not intentionally but Nacchan probs wouldn't have brought it out for once either, bc it's something she thought actually suited her, something she wanted to keep for herself, something she wasn't complaining about.