A critique for you. Again, not organized, just giving thoughts as they come up.
The stand-alone paragraph thing is a great technique, I think, but I would caution you against over-using it. I think each of the times you’ve used it would stand up well individually, but you’ve used it four times in only a thousand-word piece. Remember, this is something you use for emphasis, and it loses its effect when you see so many in quick succession.
When you talk about the proposal, the narrator describes the event in the past perfect (or whatever that tense actually is – I had done, we had done, etcetera) which lends a feeling of detachment that seems out of sync with the small, intimate details provided. If you want to keep the feeling of detachment, maybe describing the event more clinically. My instict (though of course it’s up to you) is that the narrator is so emotionally involved, it would be better to maintain that, and so it seems to me that this bit about the wedding would be better written in straight past tense.
You also seem to use a fair number of passive tense sentences. Nothing wrong with those occasionally, but stay away from using them too much, I’d say. They’re more wordy and take us a step back from the action.
I think you have pretty much a complete story here – that is, I don’t think anything else really needs to happen. It would be nice to know a little bit more about the actual argument, and it seems weird that the narrator, who is obviously very wrapped up in this still, doesn’t give the conflict itself much thought, other than telling us it was her fault. It would show us a bit more about both characters and ground us a little more in the narrator’s world. You walk a fine line there, of course. As far as I’m concerned, the story isn’t about the conflict but the aftermath, so if you do decide to do this, be careful you don’t put too much of it in there, or we’ll end up with a story about the argument and not what follows…
I think that’s about all I have for you. I agree with the comments about the piece being a bit too wordy – it’s not a huge problem but I think in a piece like this every little bit counts – and about the fact that you repeat that the narrator’s alone an awful lot. I think you could probably fix both these things with a lot of the same edits. And remember, those little details, like the empty wine bottles, the cigarette packs, etcetera, are very telling. Showing us more things like that will really drive the “alone” bit home without telling us over and over again.
Nice work.