Just to be safe, which cheats are safe to use?
If you're using the hallway cheat
The safest are Money and How rough or gentle you are
Inventory aswell, although there was a bug with, not sure if it's been fixed
as for the relationship points, which can cause it to break if overused, if you use increments like 5 or 10 at a time it should be ok.
although it really should be used in conjuction with the walkthrough, increasing it only by how much the walkthrough says.
What I do is, I do all the scenes at least once in each section first, then look at the number of points at the top of said section and only increase it to that level before moving onto the next section.
For Example
If you are starting 0.20, then each character should be at what they are at the previous section, no more
In this case that would be 0.19
Which are
0.19 - Janice:460 Julia:360 Kelly:330 Emma:380 Rebecca:300 Adrianna:175 Rachel:250 Danielle:50
Then you when you've completed
everything in the next section, which would be 0.20
Then you can increase them to the following and again, no more
0.20 - Janice:460 Julia:360 Kelly:330 Emma:380 Rebecca:300 Adrianna:225 Rachel:250 Danielle:80 Kira:10