There are no cheats to fill relationship stars or heart.
To fill up his stars hangout with him on each day of the week, each day Monday-Saturday will unlock a new cut scene which will progress your star meter. If you for example did hangout with him on 5 days but missed let's say Wednesday , because you decided to do something else then the next week you need to go visit him on the day you missed.
Also if you haven't gotten into the TV station then do that.
PS. You can get your 50k back if you do the quest for the guard in the cinema