Gemini girl cancer boy

I am a Gemini girl and I'm interested in this cancer boy.
He is the definition of confusing.
I NEVER understand him, hes so frustrating.
One minute he'll seem like we're really close, then the next its like he doesn't even know who I am.
Him and I had a thing for about a month and we kissed and whatever and I stayed at a FRIENDS house that was a guy and I told him that I did and he seemed okay with it, at first.
But then He just started really pulling away from me.
For awhile we barely talked.
He made me feel so weird when ever I would run into him, Like I couldn't even look at him.
Even though I didn't do anything wrong.
About a month of this I finally got the guts to text him and ask him why he stopped liking me.
This is what I said;
"Why did you stop liking me, and please don't just answer with a "I don't know."
And this is what he said
"Well because I changed. I decided I would rather be alone. I don't want to have a relationship with anyone."
Later I finally got him to admit that I hurt him because of me staying at my friends house.

Are cancers big grudge holders?

I figured maybe I could just prove to him that I still like him and him only that maybe I could get him back.

Please, Please help me or at least try and explain why hes acting the way he is.