The advantage of dating friends is that 1. they never break up with you if you do not date them & 2. they gain you more fans than npc's do.
It works the same as dating an NPC but 1. I don't think they have the Heart power requirement, meaning they won't insult or compliment your outfit and 2. you cannot reach milestones with them like you do with NPC's.
As for the friend having to agree, no they don't Your game and their game is completely separate meaning any actions you do with them and vice versa are only in your game and synced to the friend's, so you can date them secretly
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It works the same as dating an NPC but 1. I don't think they have the Heart power requirement, meaning they won't insult or compliment your outfit and 2. you cannot reach milestones with them like you do with NPC's.
As for the friend having to agree, no they don't Your game and their game is completely separate meaning any actions you do with them and vice versa are only in your game and synced to the friend's, so you can date them secretly