So like... before I spend more time on this... this does go more into sharing, right? So far I think I went for the "we're open about this and we find it hot" options, but like. Most of the attention is on the neighbour.
There will be different paths and sub paths.
The one you are talking about is the one referred as "NTS", we are told that there are some reworks of the story but originally there were 3 subpaths: Mila dom "reverse" harem, Mila sub gets shared around by Paul as he sees fit and Mila falls in love with Bob (which is the one I really hate

).
You also have 2 other paths:
- Loyal where Mila seems to be pretty subby
which will be more about exploration of kinks (Pure subpath) and sharong Paul (Harem option).
- NTR where the branching really goes hard: you have BBC (kinda usual stuff, but at least in this game Mila is well written) and Sugar daddy paths. The BBC branches out in camgirl (3 different endings/subpaths) and Liz subpaths
I think this is all we know for now but you're in luck since the author and the co-author are very active here and can surely dispel your doubts better than I can.