Well, a few points to address here. First, don't be hurt that your friend sighed and left the room. As a guy myself, I can say that I don't think he meant to be hurtful. In fact, it sounds like he was as composed as an 18 year old in the middle of a blow can be. The simple truth is, he either needed to go finish himself off in order to respect your wishes or he just needed to get away from temptation, again, to respect your wishes. Stopping in the middle can be really hard for a guy and he may have just done whatever he needed to do.

As for the sexual preoccupation since your last encounter. I think there's a couple things going on there.

One, a boundary was broken so now you can think about him in a sexual way whereas as friends you probably didn't allow yourself to go there (or it didn't occur to you to think of him in this context).

Two, while you were uncomfortable in the moment, now that you've had time to process it your sexual comfort level has been raised. This is why foreplay exists, we get comfortable with one level of intimacy in preparation for the next.

Three, while your hormones may be going a little crazy, emotionally you still value your friendship more than sex. It doesn't sound to me like you have a romantic interest in him so much as you have a good friend and you are convenient to each other when it comes to experimenting with your sexuality. This is a crucial distinction. You both need to understand what your choices mean to you personally and as friends before you take the next step.

Your other thread made it sound like you're not ready for sex so my gut reaction is to tell you to talk this over with your friend, make sure you're both comfortable with what happened, and then go back to being friends. I'd hold off on any more sexual experimentation. And if you don't, please use protection.

My two cents.

Be safe.

Cyran0