I read a short story online about 5 years or so ago (plus or minus a few) on a site that publishes lots of SF stories. It involved two people who could both see the future, one a girl (who is the protagonist) and one a boy.
If I remember correctly, the story starts out with the two of them on their first date. I think they're arguing about whether it was a good idea (and whether that mattered) and how their relationship will go. Their abilities work differently somehow -- I can't remember the details but I think the boy's was more specific -- and the difference turns out to be important later.
As the story develops, there is an important plot point involving a bicycle accident -- I think he damages her bike or vice versa? They do have a relationship and end up breaking up (in the manner according to her prediction, I think), which is also important. The girl has a roommate with whom the protagonist is always talking over the relationship.
There's a significant twist in the story:
If I understood it correctly, it turns out that his ability is straightforward precognition while her ability is more about being able to surf through alternate worldlines to one where her prediction is true, even if that requires a different past. From the narration, it's not clear that she even realizes this is what she's doing. The detail of the bike accident (which characters other than her describe differently at different parts of the story) clues the reader that this is what's going on.
Does this sound familiar to anyone? I think I read it around the time that Catherynne Valente's The Girl Who Navigated Fairyland in a Ship of Her Own Making was first being published in installments online, and may have even been in the same online magazine.