Dreams Come True

One-shot.
Ever since Robbie left the band, Mark has wanted nothing more than for him to one day come back. However, over the years, Mark does his best to try and stay in touch with Robbie, but finds it difficult and increasingly infuriating to do so, leaving him with no choice but to break contact for a year.
Eventually, Robbie does come back, but is it the dream that Mark has been chasing for?
(Not a great summary, sorry...)