<human>: Can you summarize the given text in a few sentences?

Hello /r/relationships!

I [19F] am in my first year of college, and have been able to befriend some fantastic people. Specifically, my question concerns a friend [19M] with whom I've been getting closer since December. That is when our involvement started.

He and I began flirting and going on dates, but I was clear from the beginning that I wasn't looking for a committed relationship. Throughout this experience, we have talked about dating and I made sure he was aware that I don't want to start anything serious. Our time together escalated to sex, and I later learned that our first time together was his first time, ever. 

Well, summer break is approaching and I feel it is necessary to cool off. However, he has said things to me that make me feel as if he will respond negatively if I express how I feel, such as playfully calling me "Mine!" and saying that he is "crazy about" me. 

I would like to express that I care about him, but I don't plan on trying to continue our pseudo-relationship while we spend a few months several hours away, and I don't wish to commit to him, either. How can I do so without damaging our friendship?
<bot>: I'm afraid my college FWB has become too attached, and I would like to tell him we need to calm down before the summer months. How can I do so delicately?