Might be spoilers....
I don't know if this has been asked beforehand but I am just curious. Are there any series of choices in Tai's route that may have led to whether the threesome will happen or not?
Viewing post in Sileo: Tales of a New Dawn comments
Not at the moment, no. I've considered going back and making the Logan sequences optional, but it's so tightly woven into the overall story that it'd be a lot of work and would require new content to fill in the gaps. It may be something we do at a later stage, but right now I think our efforts are best focused on making new stuff instead of changing old stuff.
No sweat. I understand. I thought that your choice on Day 5(Kyrex) on every route will have an impact on the story since it had on Diego's route but right now while I am writing this, I realized implementing that will be so much hassle and I understand that you are not planning on applying that mechanics in the game instead adding new contents and I totally respect that (since people are excited for other routes including myself). But regardless I still enjoy the two finished routes so far. Stay healthy and don't push yourself too hard ^_^
There will be those sorts of mechanics in the upcoming routes, there just isn't currently outside of the Kyrex choice in the existing ones. The Kyrex choice does have some impact in Tai's route, but it mostly just results in some different dialogue in a few sections throughout the story, it doesn't change the events.