The trust and corruption determine whether you can progress with certain characters and how far during the early stages of the game. Along the way, the points became too abstract and I've relied on player choices from that moment on. Sisterly Lust is my first game, so there are some beginners mistakes in there for sure.
As for the relationship status for all of the girls, they can be either yes or no, except for Bella and Susan, because they have two paths. Bella has a romance and a submissive path, Susan has something similar.
Some of the errors mentioned should be fixed in the upcoming build, by the way. Also, I while I won't be releasing any new content for Sisterly Lust, I'm going to support it, so bugfix release are still to be expected after v1.0 is released in January.
Very happy to rank so high under Katawa Shoujo, by the way. ;)