I would wait for your replay for other routes until the next update as I don't believe any of the other girls routes are finished yet. But if you have been sleeping with everyone all game, I believe week 7 is where you can decide if you are going to be involved with Melody or not and that should be your starting off point for focusing on another girl.Since now there are game overs, I'm thinking abou replaying the game in different routes (Melody, Any, Becca, etc.)
In order to not restart everything from week 1, at which point of the story I can play to take some key decisions?
And Becca in week 10 definitely thinks something is up if she has seen Amy or Melody leaving your apartment so you need to be clear of both of them to get the Becca route.