Diana is cute and good intentioned, but I can't root for someone that after all this time still can't say her crushes name right nor makes any attempt to try. Like, Lapis makes a lot of effort to get to know Natori, even if in the beginning only to manipulate her. Diana has really only been receiving. Even this right here is an example of her not really interested in knowing what Natori wants, but more about competing with the person she views as her rival. Realistically, she's kind of a shitty suitor.
I've already read that Diana's mistake with Natori's name is not because she has a lack of desire to say her name correctly, but rather the difference in status, If you notice, the only people who got Natori's name wrong so far were people with low status, because for these people the pronunciation of Natori's name is complicated so they say "Natalie" unintentionally.
If that's the case then the author has done a bad job showing it. Like, even one short scene of Diana trying and failing to say it right and apologizing would at least go some way for that. I can be sympathetic to the idea that it is more difficult for those with less education to a point, but there's a difference between someone finding something difficult and someone not putting in any effort at all.
And as someone living in the US and born outside of it, I know my name is difficult to pronounce for Americans and give them leeway with that, not really expecting people to say it right. But I have different standards for an average person saying my name, like say the maids in earlier chapters, and someone that is romantically interested in me or even wants to be my friend.