Thank you so much everyone for the encouragement. I was really scared after I got that first response.
You raise really good points and yeah ViableAlternative, I did and still do want to understand how I feel/what's going on with me a bit better before talking to him, maybe wait a couple weeks until things settle down and then I can make sure those feeling's are still there.
And yeah, he has noticed that something's wrong. We've had a couple conversations where it came up that yeah, I've been feeling kind of dissatisfied with my life, like I needed a break from it. He immediately took that to mean him and asked really hesitantly if I wanted to take a break. My reaction, as you can guess, was oh God no. I was really grasping around at straws, and there was a lot more then romantic/friendship/whatever going on, also some stuff with my course/field, at that point the whole poly thing hadn't even occurred to me.
The thing is, I am pretty sure he'd be supportive, at least outwardly. I'm also pretty sure that it would hurt him a lot. And I really don't want to hurt him.
Thanks so much for your responses and if anyone has any more advice I'd appreciate it.