Your opening meanders quite a bit yet your last sentence is a great hook (I wanted to find out why it had been six months). Like the other comments point out, you're too visual - you're not directing a movie, nor are you taking photos as events unfold, so stop narrating that way.
Rather than some abstract advice, I tried to rewrite your paragraph (I'm not yet a fiction writer, and this is a first draft):
"Laying in the dark, the outline of her sleeping figure contrasted against the dark expanse of the room. In bed together we are only a few centimetres apart, yet the distance feels much greater. It has been almost six months now. The darkness reveals just a few details – her long black hair flowing over her back and her hand near her shoulder. I imagined reaching out, holding her by her waist, closing the seemingly infinite gap, and sleeping with her in a warm embrace. Yet, reaching out, my touch had no effect at all. I’m lonely, though not alone. How much longer can it go on like this?"
I'm switching between narrating the event and the character's point of view, trying to erase the distinction between myself as narrator and myself as a character to make the situation feel more immediate and intimate. I moved your hook to the third sentence because I'm an impatient reader - I like to know bits about the point along the way as opposed to waiting for a point that might not appear to stay engaged.
Your original paragraph has some issues with spelling (Lying should probably be Laying), how you construct some phrases (I was only few centimeters of of her...), and word choice (...real loneliness was to loss someone I had, rather than no having...). These problems are relatively minor - an editor can help you correct them.
I suggest you focus on your style by dropping the visuals from your descriptions, then go back and add some visuals to clarify the situation or scene. Get an editor and prepare for lots of revisions - you'll become a much better writer.
I'm not sure what books you have read, but I recommend you try reading the classics plus some more modern books. Reading the classics (in English) will help you construct better sentences and expose you to different styles of writing. If you have already read a lot, perhaps it is a good time to re-read some passages you like (in English) to figure out what you like about them and how they're constructed. Good luck!