I believe you mean Jessica*, and to answer your question, neither path closes permanently regardless of who you choose. The only big difference is who you go after first, and in the case of picking Skylar, Jessica will be upset for a bit, and will act coldly towards you until a certain point where she will finally accept it. At the end of the day, you miss out on certain Jessica stuff by picking Skylar and vice versa. So if you want both just choose who you prefer more of the two.
If you've already played through to the point of completing the Jessica photoshoot, then you already know she's starting to warm up to you again and has accepted your relationship with Skylar. Now we just got to wait until we can finally start on Jessica's path again. Maybe the next update or two?