the characterpedia in-game, does a very decent job with providing you with hints. As long as you are actually encountering the girls, and using your powers on them, then the characterpedia will update with new details. That is your walkthrough.
example: Talking to girl until she reaches next level of affection. Then girl has conversation where she says she likes to go shopping at the mall around 2pm on Saturdays. Characterpedia updates to include a note saying to see her at mall at 2pm Saturday. You also get a BIG yellow star on the map on Saturday around 2pm (if you are close enough or have unlocked the spell to see target farther).
All together. The Characterpedia is decent walkthrough. No requirement for much else. The few brief walkthroughs and tips around, refer to the very few time sensitive quests. Last I remember there were only 2 I think. They are not game breaking. It is just an in-game counter to permit player to alter the outcome of a scripted event. example: one girl is getting married in a month. So you have a month to change that outcome, if you care.