Re: Randori, Sempai and experiences
This one is a tough one, partly because I feel like I know you a little bit from all the time online where we have corresponded. Frankly, I think the other guy was an idiot, and he's probably lucky he had you as his partner...some others would probably have slammed him and moved on.
Are you allowed to do much talking on the mat in your dojo? It may be that actual verbal communication was called for here, on the side, away from prying ears. Especially since you asked to go slower and he seemed by his actions to refuse. At some point, if that didn't work, I might have just told him I was going to join a different group, as I wasn't profiting from my time with him.
I have been in situations where on a particular day, some particular partner and I just won't synchronize for what ever reason. Generally one of us just switches with another group, or we both back off and take it easy. It's always embarrassing when that happens, but I try to remember that embarassment is not big deal, and beats injuring or being injured.
Ron (maybe let it settle, and then speak to your teacher about it some more...direct questions like what would be a better approach...)