Only one hearth? Man XD. Ok. You need more followers and suscriptores and be more lascive with Anna, you need to take the photos with the border pink from pasion. Go with her to the park and just walk with her for pasion or take photos for subs (better pasion). After that you can select if you want the pure route or the slut route. For one hearth you need followers, for 2 hearths you need subs, for 3 hearths you need followers, subs and pasion if I don't have a mistake; and for 4 only complete the story. Take this, maybe can help you:
Thank you so much, you really saved my life! But I have an issue with the quests in the game except for Anna’s quest. There are many quests listed, but I can’t progress in any of them. I do what the quest asks and go to the locations, but the quests don’t advance. How can I fix this? Also, thanks again for explaining how to solve the heart problem in Anna’s quest
Since the game isn't finished yet, many quests aren't available. You can ignore the in-game notepad. Here's a guide for your reference.
https://docs.google.com/document/u/0/d/1LkXWll0_8kVL23hHWWySoRwKL_4dyluPHeLQsnhv...
Well, it's strange if you can't complete any mision. But some missions require Anna's progress even if it's not specified. So that could be the problem, or you might be missing something else. Stuck missions are rare, unless you're bugging the game with Unity-injected menus. Upload Anna's progress and try again, and it might fix it.