Miss someone I ve never seen online.

[Bookworm]

Its not healthy being fixated with someone who is not interested in you; its not good for your self esteem and it is just counter productive and will mess with your head. Its difficult but you need to move on and just put it down to experience.
I would focus your energy towards something more positive; catch up with some close friends and have some quality time with people you know that care about you.