Ok i figured it out you need to play enough to the point where you take control of Faylen as a spirit. Then you need to level her up to level 20 (max level) and use her skill to reveal hidden things inside of the prison place guarded by the squid thing. After you do that you will be put into a boss battle and after you win you get some kind of ring from him. After that if you ask how to improve your relation ship with Selena it will say visit her in your dreams. Thats what I did at least so I think it should work.
Edit: after I went to the dream world when you ask to leave its different. you will know its different because they talk about nel