The game uses relationship points system.
If you've made a right choice, there will be red heart with that LI's name and a plus sign with prompts up and disappears instantly:
Luna (red heart) +
As
whichone just pointed out, there is no issue with rollback with this game (in fact, I don't think it is an issue with most renpy games), but if you're worried, you can always save at the dialogue decision point.
And like I've been saying dialogue choices are 'easy peasy' that a guide is pretty much obsolete for it (and if there is a bad choice, you can pretty much tell which one not to pick, with common sense).