Alright! There's a lot to unpack here! <3
So yeah, the options can be broken down to friends, friends with benefits/lovers and kind of "meh, it's you."
The characters should NOT be able to trigger intimate scenes if you never flirted with them, and you're absolutely right: The "we're going to die, let's live without regrets" setup was an intentional and plausible reason to remove any relationship obstacles to intimacy without having it feel rushed. (–In my opinion. It's interesting that you mention it feels rushed to you, several people have voiced the same opinion, while several others have claimed that it's way too drawn out, and then several others have mentioned it feels perfect. Such is the ways of internet feedback.)
The friendship option still shows the flirting options to simulate the whole friends to lovers dynamic, but if you never pick a flirt option, you should remain JUST friends and intimate scenes won't/shouldn't trigger. Initially the not interested option functioned the same, but I had to change it as some players were legitimately frustrated, especially when they were doing a playthrough as a straight male for example, and continually kept seeing the flirt options despite choosing "not interested."
If you have any specific scenes that felt out of place for you character's personality, please let me know (you can do so on our discord server), along with how you feel your character would have reacted in the situation. It's not always possible, but sometimes it is and I love to add fixes like that, even if they are done retroactively. You can talk to several of our other fans, adding choices/content like that happens more often than you think!
The romance options were added due to market demand. I've always believed that Infinite Stars should have a strong story, even if you were asexual and not interested in any romantic options, and I feel I've achieved that to a sense. I also feel that the romance options are little stories on their own, running parallel to the main story, and that the free version of the game (without any intimate scenes) should be able to give a full and wholly enjoyable experience without having to pay anything, while still rewarding the super fans willing to support the development of the game with something special and extra (the intimate scenes.)
Part of my original design document states that there will never be any crucial main story plot developments that occur ONLY during an intimate scene, as free players won't be able to experience it.
I'm quite excited for the content we're currently working on. I hate building hype, as it's so easy to overhype something, so I'll try to cone across as unexcited as possible: With Veera's intimate scene(s) we've been working on, she has a whole story arc how she changes as a person, with each intimate scene slowly chipping away at her masks and revealing the woman inside the assault armor. Veera will still be Veera, but you'll have a better connection and understanding of her after going through her various intimate scenes. There are also some scenes which are 100% fanservice scenes that aren't taken as serious. (Sometimes it's just fun to write (and play) silly yet hot romantic kissing scenes to take a break from the tension of the story!)
There aren't any professional aspirations when it comes to writing Infinite Stars. I break TONS of writing rules deliberately because it shouldn't be a chore to me, and it's not trying to be anything else than what it is– a fun hobby. It started as a hobby, and I sincerely hope it stays that way. There is so much planned story in my head, and the day when there are no more new ideas or if it's no longer fun to write is the day that I'll neatly wrap the story up.
Apologies for the ramble, it's been a day and a half for me! <3