Is there any guide to reach each route for book 2 and further? All I got from github was basic mechanic explanation but from the gallery theres plenty of endings which I assume needs different approach.
There's really not that many endings, and the choices for endings are so obvious that it's easy to know what is going to happen (for example, B2 Love gives you a choice to pick Azula, Mai, or to run away. This choice is: "Do you want Azula, Mai, or both?"). Also, for just about everything in the game, you are
explicitly told what you need to do to progress. If you read the dialogue you
WILL be told what to do next in 99% of cases. If all you want are the sex scenes there's a gallery mod in the first post on page 1 that will unlock everything and all the variants of the scenes. The gallery mod is great and really well done.