How can I communicate in my relationship better?

I tried talking to my boyfriend about his day today. One of the things he mentioned was that he went to the gym. I asked him questions about it and talked to him about it and at some point he told me to stop talking about it. He does this often to me where he tells me to stop talking about a particular topic after x time. He specifically says “there’s nothing more to say.” I tried talking to him about this response that he often says to me and how I can prevent our conversations from coming to the point where he feels the need to say this to me and he tells me that he can’t think of specifics but that I just have to stop talking about a topic when he says to. He did mention that he thinks I push for way too many details and that I talk any topic to death. I feel that it’s fine if he has nothing more to say about a topic but why does he have to keep me from talking about it more with him? I mean this is confusing to me in general because I never experience this kind of response when I talk to others. I don’t feel that I push topics to death with him nor with other people (as no one before has ever told me this before him) and so I don’t want him to feel this way but I don’t know specifically how I can change my behavior to prevent when he feels I am talking too much or asking too many questions (before he outright says this to me). Where is that point for him? He won’t say. So how can I change? No he wants me to stop talking about something when he wants me to stop and won’t help me improve as a communicator (before he gets annoyed with me or a future person might since in his opinion he says I have a problem with being pushy). Like when I asked him how I can prevent him from feeling this way around me he only said that I can just stop talking about a particular topic when he says to. Yet he won’t stop me from getting to that point where he feels pressed by me. How can I stop this kind of thing from happening if he doesn’t tell me how I can improve? I just want our communication to be better where he doesn’t end up feeling like I’m talking endlessly about a topic and just wants me to stop. All I simply want is to do my part. Sorry for the long text.

from,

a socially clueless woman