What does a guy mean when he says I don't want to have this conversation again for a while?

Ok,

So this guy and me have an interesting relationship. We do everything together practically, cook, eat, travel, go shopping, the works. The only problem is is that I have feelings for him and he claims to see me as a little sister. Recently something happened that put me in a difficult position and I had to make a difficult choice. It was right after I got rejected and the choice determined both our fates. I didn’t know what to do, and was leaning towards just saying good bye and never looking back. Anyways I chose the latter, and it was alright for a while but then he asked me why I chose what I chose and when I told him it kind of overwhelmed him. I’m not really sure where to go from here.