I still don’t understand why the boys are the ones to come apart. They entered the “time loop day” from the timeline in which there had been no train wreck (which is why they came to the past to cause one). The girls, on the other hand, came into the time loop day from the timeline in which there had been a train wreck, which is why they keep coming back to try to stop it. Now that the wreck has been averted, the time loop day leads to the no-wreck time time, which is the one that the boys came from. So they aren’t in the “wrong” timeline at all! Why, then are they breaking up?
I still don’t understand why the boys are the ones to come apart. They entered the “time loop day” from the timeline in which there had been no train wreck (which is why they came to the past to cause one). The girls, on the other hand, came into the time loop day from the timeline in which there had been a train wreck, which is why they keep coming back to try to stop it. Now that the wreck has been averted, the time loop day leads to the no-wreck time time, which is the one that the boys came from. So they aren’t in the “wrong” timeline at all! Why, then are they breaking up?