It takes time, just try to make the image appear gradually. Don't rush it.
So... just do what I'm doing? Having conversations with him in my head?
Yes, let him become apart of what you know as the real world. Open your minds boundaries and let him through (a weird way of saying, trick yourself into thinking he's there).
How do you "open your minds boundaries?"
See the image of him/her in the real world. Let the imagination move into the real world.
I hope you meant love in a good way.
So, like, with my eyes closed, imagine a place (say my room) and visualize in my head my room with him in it and have conversations with him?
"trick yourself into believing it's real"that doesn't sound forgeted to any of you?
It's all about changing how your mind perceives what is real and what isn't.
Yes. Then I would begin to allow yourself to think he is in the room with you when your eyes are open.