Justin is a ghost who lives in the studio of his old family home. I think he feels he was abandoned there. Brian is looking for a house and Jennifer shows him her old home, where she's not aware Justin's spirit is trapped. Eventually B/J meet, fall in love. Brian is the only one who can see him, but they have a tumultous relationship. Something about lots of food but Justin can't eat, and jealous Justin queening out in the studio. Eventually Gus believes in Justin's existence. At the end Gus is married with kids and Brian somehow joins Justin.
I couldn't find it in the b/j is a ghost/spirit tags. Help?
FOUND already by the expeditious ara_kiss. Love's Not Time's Fool by Wren. Link in comments.
Thanks so much.