A couple of points to bear in mind:
+If the conversation isn’t mentioned below that means it doesn’t change how the character likes you – it’s just for roleplaying purposes.
+There is no set order the characters need to be played in, but the secret romance will not be available as an option until all other romances have been completed. He is well hidden for, I think, obvious reasons.
Bastien Aubert
Day 1 – “I Will” or “Oh, I intend to do more than that”
Day 2 – “You are not having dinner with us?”
Day 3 – “That does sound quite nice.” then “I suppose so…”
Day 4 – “Do you honestly want to talk about the Prince?” then “Become angry”
Day 5 AM – “Yes, but it is not so simple.” or “Yes, I miss the closeness we once shared.”
Day 5 PM – “Remain in my apartments” then “Because you could be anything!”
Day 6 AM – “GETOFFMYBROTHER!”
Day 6 PM – “And Master Bastien will be dining in here with us as well.” (if you do not invite him then the romance will end) then “No” (if you choose “Yes” the romance will end)
Day 7 – laugh
Day 12 – “Means nothing without you.” (if you choose “Is none of your concern” the romance will end)
Lady Charlotte De Souza
Day 2 AM – “Attempt to join Charlotte, Francesca and Albertine” then “Calm yourself. I won’t say a thing if it distresses you so.” or “Don’t be silly; she will find it amusing”
Day 2 PM – “I’m scared! Get it away!” or “Faint” or “It is merely a bee”
Day 3 AM – Play croquet with Charlotte then “Coach her through the game.”
Day 3 PM – “Go outside” then “visit the topiary” then “Because we young ladies are seen as too delicate.”
Day 4 – “Of course!”
Day 5 AM – “I am fond of her, but it not so simple.”
Day 5 PM – “Take a walk in the grounds.”
Day 6 AM – “Faint”
Day 6 PM – Visit Charlotte (if you do not visit then the romance will end) then “Why?” (If you pick “Indeed. And the practicalities of these adventures far outweigh the pleasures.” the romance will end)
Day 7 – cry
Day 11 – “I love you, too” (If you say you want to marry the Prince or “I’m sorry, Charlotte, the romance will end”)
Prince Guillaume
Day 1 – Any barring “Well, at least there’s plenty of totty to admire.” or “Oh, I adore gatherings like this ? you can learn all sorts of secrets.” or “Well, the room is laid out all wrong and the decorations are too gaudy-“
Day 2 AM – Just walk alone then “Perhaps it is, if you are the only one to be burned by it.” or “And what does your Highness think?”
Day 2 PM – “It is merely a bee” or “Leave it alone. It plays an important role in this garden.”
Day 3 AM – Play croquet with the Prince then “Suggest you play terribly”
Day 3 PM – Explore the palace then “I feel rather discomfited”
Day 4 PM – “You are not used to ladies fighting over you?”
Day 5 AM – “”I like him, but I have no desire to be queen” or “I would wish to marry him whatever his station”
Day 5 PM – “Visit the Music room” then “Enter the music room.” then “My mother wished to set me apart.” then “(Truth) Because your Highness began learning the piano.”
Day 6 AM – “Unhand him at once!”
Day 6 PM – Visit Guillaume (if you do not visit then the romance will end)
Day 7 – cry
Day 8 – “Then you are forgiven. And I apologise, too, for my own part in the argument.” or “I cannot forgive you. Not until I know from where it stemmed.” then “His Majesty is correct. (Lie)” or “Your Highness is correct.”
Day 12 “I confess, I do” or “No, but I want to be queen.”
Duke Leopold Stavizzi
Day 1 – Any barring “Why, I don’t know what you mean” or “None of your business”
Day 2 AM – Try to catch Leopold’s eye then “I wish there were a bit more to do.” or “I prefer more cerebral diversions.”
Day 2 PM – “Faint” or “Have you heard about those awful Aphesian bees?”
Day 3 AM – Play croquet with Leo then “I will not hide my talents for the expectations of others.”
Day 3 PM – Sabotage Albertine’s tea party then “No, I was just sabotaging Albertine’s tea party.”
Day 5 AM – “I like him very well” or “I like him but it is not so simple”
Day 5 PM – “Visit the long gallery” then “As you wish”
Day 6 AM – “GETOFFMYBROTHER!”
Day 6 PM – “Visit Leopold” (if you do not visit then the romance will end) then “Here, let me clean it first.” then “Why do you even care what the King thinks of your House? ” or “I am sorry…”
Day 7 – laugh
Day 8 – “Do you take pleasure, I wonder, in reminding me I am stuck?” or “If you think my mother can force my hand in anything , you are mistaken.”
Day 9 – “I would like that” then “So what if you are?” or “Are you?” then “Yes”
Day 11 – “I am quite impressed” or “I understand, but I can’t bring my family into something like this.”
Day 12 – “I do, with all my heart!” or “Leopold, I love you, but it is not as simple as that.” then “Then I accept!”
Sofia Venitti
Day 1 – Either “Why don’t you tell me more about your theory?” or “Say whatever you wish; I have no intention of pursuing the Prince anyway.”
Day 2 AM – Try to get Sofia’s attention then “Then it seems those parks would have something the royal gardens lack.” or “That sounds like something I should like to experience.”
Day 2 PM – Either “Leave it alone. It plays an important role in this garden.” or “It is merely a bee”
Day 3 AM – Play croquet with Sofia.
Day 3 PM – Go outside then visit the lake then “But why run the risk?”
Day 4 – No choices make a difference
Day 5 AM – “I am fond of her, but it is not so simple”
Day 5 PM “Go to the Library” then “Tease her more”
Day 6 AM “Unhand him at once!”
Day 6 PM “Go and visit Sofia” (the romance will end if you don’t go.) then “Comfort her” (The romance will end if you “Leave”) then “Friendship… Is that all we have?”
Day 7 “Cry”
Day 12 “…Yes, I do.” (“You are mistaken, brother” ends the romance)
Secret Romance
Complete all other romances, then in the first carriage ride on day 1 select the option “Please don’t ask me that” to activate the romance.
Day 3 – “Frederique…” (“Behave yourself” will end the romance)
Day 4 – “I’d like that” (“I don’t think that will be appropriate” will end the romance)
Day 6 “How can I say no to that?” (“No, Bastien is right” will end the romance)
Day 7 Either “She would be a good match” or “No, I suppose not” (“Of course. You will have to marry one day.” will end the romance)
Day 11 “No” (“Frederique, we can’t go on like this” will end the romance)