As of 0.13 (upcoming update), main or side LI's aren't explicitly labeled, though you can probably guess who will get the most screen time.
Since there will be new girls added in 0.14, I will split the gallery into Main and Side girls for better clarity.
As development goes, "side" girls may become main ones and have a more complete solo route!
Hey dev! I just finished V0.11 and I was looking through the devlogs. I hope you don't mind, this is just an observation, but V0.12 has been on Patreon for about a year, while the general public only got access to V0.11 a little over a month ago. Is the release schedule going to be like this, with about a one-year gap between the Patreon version and the public version?