Yes, it may feel that way, but she's also struggling with this. I'm not sure if you played 0.3.0, but she's really confused and having mix feelings about MC and MC Hero. She's starting to realize about her feelings at the same time, that she knows it's impossible. Going behind someone else, may help her overcome the feelings she has for her brother. I'm not saying this is the way or anything, I think all ppl has its own pov and likes/dislikes. Maybe I should have worked their hero story a little more before jumping to a first kiss. But it felt correct at the moment, and I can't undo what's been done.
But I really picture this from her side, she's been always there for him, but she knows it's not happening, he's in another "level" for her. His worries, for her, are saving the world, training and getting better. In most of the scenearios Kate can picture, she's only "The sister of that dude trying to play Heroes and Dragons". She needs to move on, and have her own life. Of course, at the same moment, she wants to be part of his life, that's why she's trying to become something like MC (a Genex without Genex).
Once again, I'm not saying this is the way, but this is the love story I thought for Kate's branch, trying to leave the ordinary sisterly love route from most games I played (which are really only a few, I actually dislike playing VN....but that's another topic).
The last version I played was 2.52, so sorry if some of my complaints don't apply anymore in 0.3.0, as I didn't play it yet and don't know what happens.
But again, i don't actually dislike how their story unfolds, i think it's interesting for them to get to understand their feelings to each other via them meeting and being attracted to their secret identities. I just feel like it's at least a bit jarring that she doesn't question herself even a little bit earlier, like, going back to the kiss for example:
She goes to that party looking specifically for her brother, she probably wouldn't have even gone there in the first place if it wasn't to try and surprised him with her costume, and yet when she doesn't seem him there she's like "fuck it, guess i'm with the hero now" and the she's 100% ready to kiss him w/o even 1% of regret over having her first kiss with the first random hero she saw doing his job on the street, like, at that point she barely knows him, would she kiss anyone as long as they saved her once and was relatively nice afterwards?
I'm not saying it shouldn't have even happened in the first place, but things like her first reaction after it happens being: "wow, so that's how it feels to kiss someone with superpowers, huh?" Instead of: "shit, should i really have done that? That was my first kiss" or the fact that she doesn't really even hesitate to do it, knowing she's not only in love with another guy, but also completely inexperienced make it feel odd to read.
I think the disconnect of 1- How Kate actually feels (her feelings of thinking her brother is completely off limits and how she's struggling with knowing deep inside her that she can't be with him the way she doesn't even know she wants, but yet wanting to be by his side to support him in whatever he needs as his sister) and 2-The way that it may come off as a reader, originates from a lack of clarity on what's she's thinking at that point, sure, I as a player already came to the conclusion that she's in love with him beforehand, but then when i see he doesn't come to her mind even for a moment when she's flirting with a new guy it just makes me question if I was wrong from the start, I mean, there's no way she's in love with him but she forgets all about him immediatly when he's not literally in front of her eyes, right?
I can almost understand her not thinking too much about it in the heat of the moment with the kiss, sure, I feel like she would have thought a bit more about it, seeing it's her first ever kiss, but alright, it can happen. And yet when she comes to her house hours later she still doesn't think anything about it, her biggest concern is: "How much of my boobs should i include in this photo so he doesn't think i'm a slut and keeps talking to me?". She never questions if she should be flirting with him given she doesn't know him. Or when she's training, she does think a bit about Marco and mentions how she is training to one day help him, but yet the thought never passed her head: "What would Marco think if he knew i'm meeting this guy i barely know, alone in an abandoned warehouse, in an outfit that barely covers me, knowing full well he's interested in me in that way due to all the flirting?"
Again, i haven't played 0.3.0 yet, maybe this issue is completely resolved at this point and we get to see more of her internal struggle, but even then it feels strange that she never thought about these things even a bit earlier in the story, like when she thought to herself "I can't tell him about the hero", maybe it was a missed oportunity for it to be something like: "I can't tell him about the hero
he wouldn't understand, I'm meeting with him to be able to help Marco one day, but i know he would worry about me being alone with him......... Wait, what am i thinking? Marco is my brother, he wouldn't be jealous of me like that,
would he? Get your head out of the gutter Kate!" instead, you know?
Maybe you completely disagree with me, it is understandable after all, as you said, different people may have completely different points of view, and thus I'm not saying these issues I see are something that you have to fix, as it may not even be an issue for you + this is one of my favourite games in this site at the moment, so I wouldn't want you to feel pressured to develop certain story lines in the future while trying to mind what other people may think about them and limiting yourself thanks to it. What i'm trying to convey is why this specifc part of the game feels strange to me and why I think some people may have the same feelings I have about it. Not trying to say that what I think may be better for some dialogues is actually better for the whole story, as I don't have the whole information of how it will unfold, who knows, maybe if she did start questioning things a bit earlier it would end up making the story less compelling in a way? Something like players asking themselves: "Oh, if Kate know her brother may dislike her meeting with the hero why doesn't she just
ask him in the first place???"