From Andy Snow, Chicago:
(Spoiler warning) The "improbable chance encounter with Michelle" described in your review of "Boy A" isn't an actual encounter at all. If you observe the adroit manner in which light is used in this particular scene, it is evident that Eric/Jack is only imagining that Michelle is there. Plus, there's no way she's actually there; she had no way of knowing he was going to be there and she had no reason to get on that train, although the main evidence for this is still the simple fact that you can just tell from the shot that it is just something that is happening in his head. In fact, that entire final sequence in the film is all about what is happening in the protagonist's mind and the avalanche of emotions that comes as a result of all that's happened to him.
Ebert replies: I'm not aware of any critics who pointed that out. But you may very well be correct.