Penelope and Junior

I've always wonder if Penelope and Junior were going out or what? Because it never really says but it does say that they kiss. It doesn't seem like their going out because it doesn't mention her alot after the night where they went out to eat and Rodger gave Junior a ride back to the rez. Did Penelope ever go out to the rez to see where Junior lives at? And it seems kind of weird how they had a thing going on after Junior discovered her throwing up in the bathroom at school. Was it because of what he said to her or something else the author doesn't tell us?