<human>: I've been with my girlfriend for 3 years now. We started in senior year of high school and now are juniors in the same college (she transferred to my college after a bit for her own personal reasons, it's not an issue in our relationship)

We're the first people we've each been in a relationship with. First kiss, lost our virginity to each other. 

We're both going abroad next semester. Spain and Germany respectively.

I'm having trouble. Because it was my first relationship I'm often thinking about other people. Not specific people but types of people. For example I am in an activist group and my girlfriend doesn't care much about activist issues. So I imagine being with someone who cares about that. Or someone who is funny in the same way. Or someone who has different physical traits I find attractive. It's never that I wish I could be with someone else I met, but rather that I fantasize about being with the sort of person other people are, if that makes sense. (like a redhead who cares about activist issues, ie someone my SO isn't)

But through all that I'm never happier than when I'm in relaxing in bed with her. Not doing anything sexual really, just like talking and in bed together. She makes me so happy it's hard to explain. 

I still have those thoughts of trying new things and how I wonder what it's like to be with people who are different than her. It's consuming. There are constant thoughts.

What should I do?

Condense the text into a few key points
<bot>: In a long term relationship, with the first person I am in a relationship with. Fantasize about relationships with non specific persons with different attributes but am very very happy when I'm with my SO. What do I do?