A girl gains Affection (hearts) over time when her "Liked Traits", i.e. preferred Stat, is above 0. The rate increases with the current level, and is affected by current speed. This is the only idle way to gain Affection, although it is very slow at first.
It is impossible to unlock a later hobby without unlocking an earlier one (e.g. Fumi does not unlock Smart or earlier but you need Smart in order to unlock Fumi).
The quickest way to unlock all the hobbies is to unlock Wisdom (preferably Cassie Crush), then Elle (Wisdom level 2), and then get Elle to Awkward Besties.
The current hobbies are:
|Stat Increased||Hobby||Unlocked At||Girls who favorite it|
|Buff||Surfing||Cassie Frenemy||Cassie, Nutaku, Sutra|
|Tenderness||Sketching||Cassie Friendzoned, or Mio Nuisance||Alpha, Q-Pernikiss|
|Motivation||Protesting||Cassie Friendzoned, or Mio Nuisance||Iro|
|Wisdom||Meditation||Cassie Crush, Mio Awkward Besties, or Quill Frenemy||Bonnibel, Ayano|
|Badass||Bow Hunting||Cassie Crush, Mio Awkward Besties, Quill Crush, or Elle Awkward Besties||Pamu, Luna|
|Smart||University||Mio Crush, Quill Crush, Elle Awkward Besties, or Bonnibel Frenemy||Fumi|
|Angst||Brooding||Quill Crush, Elle Awkward Besties, Bearverly Frenemy, Bonnibel Acquaintance, Fumi Acquaintance, or Nina Nuisance||Eva, The Dark One|
|Mysterious||Vigilantism||Elle Awkward Besties, Bearverly Frenemy, Fumi Acquaintance, or Nina Nuisance||Nina, Karma|
|Lucky||Sky Diving||Elle Awkward Besties, Bearverly Awkward Besties, or Nina Nuisance||Quill|