I need to apologise so much for taking so long with this, lovely. I have no excuse at all and a month is far too late, really, so you have my sincerest apologies for my inefficiency!
I've not got a great deal of experience in reviewing OF, I must admit, so I'm not too sure whether this will get close to my normal type of review on HPFF, but I'll do my utmost for you now :)
For the most part, the flow was really fluid and smooth. You do, at two points, switch tense and I can't work out whether it's intentional or not. Here, and then again later:
Should I really give Chris a second chance? Am I really ready to say good-bye to our relationship? After all, I had been in love with Chris before he told me about kissing another girl, my best friend to be exact.
Because the story is retrospective, I understand the present tense at theend but here, it felt a little strange. If it was intentional, perhaps editing the formatting would clear that up? I'm not sure but it stilts the flow a little.
There is the occasional typo, possibly where you've gone back to edit something and forgotten to delete a word, or not finished a sentence. It's nothing that a quick read won't sort out - also, you've left a bit of BBCode in around one of the words. That's not really a big deal but I thought I'd point it out!
Narration and Characterisation
Okay, so the retrospective narrative worked really well here, with that final paragraph really helping to define it and make it clear. First person can either really work or really not, but here I think you've done really well. It's allowed Dawn's character and strength to really shine through, and she is well-developped, considering the length of the story.
Although first person often limits and tints the reader's view on the other characters, I think you brought both Chris and Ali off very well. There's an evident good side to both of them as they both recognise their wrongdoings, and that's really good to see. It's quite easy to obscure the truth through the biased narration but it really works well here.
Dialogue and Description
This is probably the part that needs a little work. I'm not a dialogue expert at all, unless it's strikingly obvious, but this read really well to me. It seemed natural and flowed very well.
The description, however, seemed like it was lacking and I think you could improve on it a little. Just take: "Then let's build some more trust," Chris said, continuing to push the matter further. Here, it's obvious that he's pushing the matter further from what he says, and telling us is unnecessary. However, you could build on this really well by expressing Dawn's sentiments towards it; how she feels at that moment, whether it reminds her of anything else that's happened before, how he says it - tone, pace etc. They're little things but I think it could really make a different to how the entire thing reads.
I'd have liked to have seen perhaps a little more of the setting, character description - just in passing, since OF makes it harder to picture them - and so on, which you could really build on with the framework you have here. It won't take much, but I think it would perhaps give the piece a bit more bite.
I hope this is okay, lovely. I'm not sure how formatting works in reviews here so if this reads with big gaps or as a huge block of writing, I'm so sorry! I hope I wasn't too harsh and if you have any questions at all, just give me a nudge and I'd be more than happy to help :)