I've reached lvl 3 lust, lvl 3 passion, strength 3, agility 3 and intelligence 5 and yet i can't access the blue boundary because i don't have the aquamarine fragment??? I heard there should be a scene once i sleep but i don't have anything in my inventory? Someone pls help

Keep doing the special workout with akane until you go to fortress with her. After that you can freely access the blue boundary.
For goddess dive you have to talk to Minerva, choose the "passion" dialouge option and complete the quests she gives.