Okay, first off... I have never written a critique before so bear with me. This is quite a step up from the Mibba comments I'm used to.

I love the imagery in this. The choice of adjectives and adverbs is remarkably effective. It gives a real sense of the mood and atmosphere of the piece, and the scene in which it is set, right from the opening paragraph;

Loud music filled the dimly lit room and drowned out all other noise. Colourful rays of light drew intricate patterns in the haze. The stench of sweat and drinks lingered in the stifling air. A chaotic mass of limbs and bodies writhed on the dance floor.

I also admire the clever use of similie (sp?) and metaphor. This, combined with the powerful language, also adds to the mood. One of my favourite examples of this would be;

His gaze wandered across the dance floor, across the dancing crowd. United by rhythm, one body blurred into the other, until they moved as one creature, turning, twisting, writhing with ecstasy or torture.

The use of the contrast in the phrase "ecstasy or torture." is brilliant, showing how two completely opposing concepts are so easily confused, much like love and loathing, and also (in my opinion) link integrally with the main theme of the work (love, as I understand), since it is an emotion that can cause states of both ecstasy and torture, as is also depicted. 

Which brings me neatly and finally onto the most effective use of language. The way the emotions of the character are conveyed is very well done (if that made any sense to anyone). The way the language is used perfectly suits the way the character is feeling. The scene is portrayed in a negative light because the character is in a negative state. All the vocabulary points towards a tortuously low mood.

Infact, thinking about it... I'm struggling to find a criticism.

All in all, an excellent piece of writing.

 Very interesting scene, well set.  But we don't know why the breakup happened, what she did.  He seemed so committed, so totally with her and she seemed in the beginning to be perfect for him.  It doesn't seem quite believable to me without some explanation that she would simply leave.

What had brought him there? How did he end up like that? He barely remembered. But all that mattered little with the music beating a violent rhythm upon his aching head. If only it could drown out the noise of his heart.

I like the rhythm here, and indeed, I like it in the whole piece.  I can really see this suffering guy.

He wanted to drop the glass, throw it away, smash it against the wall just to hear it burst, have the high-pitched chime pierce his ears and right to his soul.

splintering sound, shattering glass, something else -- chime doesn't say breaking glass to me.

 United by rhythm, one body blurred into the other, until they moved as one creature, turning, twisting, writhing with ecstasy or torture.
The music changed, and the beast disappeared, separated into a multitude of beings, each as terrifying to behold. Radiant wings surrounded some, bathing them in eternal light searing his mortal eyes. Halos of shadow obscured others, hiding their form and turning them into hideous abominations of pure darkness.

An interesting morph -- I would take out the "as"

a lithe panthress clad in flowing white silks.

How about panther/woman, maybe even pantheress, but I don't like that either.  The juxtaposition of black panther and white silk is interesting, but I don't know if it was intended that way. 

The Latin didn't work well for me; seemed kind of irrelevant, but the consistent kind of reverie-language gave the piece the necessary unity.  Now I have to go read what else you've written.

Nice work here. You clearly have a strong grasp of imagery and description, and I enjoyed what you put together in this piece. I particularly liked the way you described the dancing crowd as well as the general atmosphere of the room.

What I think could use work is the general structure of the story. I understand that it is flash fiction and thus meant to be something of a snapshot, but that does not mean, in my opinion, that it should lack the narrative quality that makes a story effective. It seems that much of this story is a background, or a very dramatic introduction to what turns out to be a very small bit of action or movement. What you're describing here is mostly a situation, and while I found it very interesting, the ending disappointed me. It doesn't have to be happy, or even reconciliatory. It could raise more questions than it answers. But in the end, something should happen that makes the story more of an event and less of an exercise in writing.

I think one way of accomplishing this would be to carefully pace the dramatic language of the piece. If you were to begin it more subtly and then build up to something it would give a much greater sense of progression and narration. The protagonist here clearly undergoes something dramatic and noteworthy. Perhaps the event of the story would be to make the reader feel the leap that the character takes. Instead of having it be a storm from the beginning, give us a sense of build up.

All this would require is some muted language, perhaps while you are establishing with a bit more clarity what exactly is going on in the background. With the right choice of words you could have the situation be as mysterious as it is now, but not entirely inaccessible.

That brings me to the fantastical imagery that the story culminates in. I think it's role should be clearer and more coherent. As it is now it seems arbitrary. With a better understanding of the character, and perhaps a better understanding of the significance of the imagery that you're putting together, you could achieve a very real effect with such surreal images.

Thanks for sharing this. Like I said, the imagery and description is solid. Hopefully this critique is helpful in putting them together a bit differently for a stronger finished product.