Ugh, I hope not
You can be individually with each of them by choosing their specific route and it's way better that way
I wouldn't want this game to go full polyamory at any costs
i don't see the harm in having it as an option, though i think the characters are too jealous for it to really work within the span of the game, i'd like to be proven wrong though and have it be an option. though it would also depend on what exactly the options are, since i'd really want gil/walter/lars poly, but andeh has suggested that gil/lars is over. andeh has also hinted at walter separately dating gil and parker simultaneously, which i don't personally care for.