<human>: Can you give me the gist of the text in a nutshell?

I've[M19] been with my current girlfriend[F18] for about a year. She's a senior in high school while I'm a freshman in college. We still live reasonably close, 45 minutes, that I'll see her on weekends with no trouble. I'll also call her every night before I go to bed at the dorms. 

I love the relationship. We're compatible and it's a lot of fun doing anything with her. We go on dates. We'll play games together. Sitting around watching movies is a great day. We do the same sport. (At reasonably high levels. We both made nationals, so practicing together is really fun). The issue I have is whenever I have to leave her.

If we go on a date, it's a night I really enjoy. Everything seems perfect and we're having fun. But then I drop her back off at home and she gets super sad when I walk her to the door. It kills the entire happiness that I had gotten from the night.

I'll call her every night for about twenty minutes to just talk about our day. But whenever I'm about to leave, she'll get really sad. It's like those girls who say "Nooooo, not yet. Five more minutes." And even if I do stay for a bit longer, she still gets sad and says goodbye like her world is ending. 

After we spent an entire weekend together, she got super upset when I needed to leave. She said, "I just really don't want you to leave.." In a whiny voice. Her eyes would go all downcast and it would just be a pain to leave even though I needed to get back to school.

Before, I thought it was cute, because it seemed like she actually liked me a lot. But now, it gets irritating because it kills whatever happiness I got from hanging out with her.
<bot>: Girlfriend gets really upset whenever I have to leave her, regardless of the situation or what we had been doing, and it makes me upset.