how do u have the scene me i don't have the scene
You need to have had the scenes where Julie almost walks in on you and Linda in the bathroom, as well when Julie walks in on you and Linda in your bedroom. You also need to have reached the "end" of Linda and Julie's solo storylines. I'm not sure if you need to have had the scene with Julie by the pool during the day.
Keep talking to Julie, she will give you instructions to watch her in the pool at night.