What does my boyfriend mean when he says "I don't want to talk about it"?

[Tadakatsu Honda]

When my boyfriend and I are debating or arguing our individual viewpoints on a subject, he generally closes out the discussion with "I don't want to talk about it anymore" when I have stated my point of view and backed it up with supporting evidence. I take it to mean I am right because he does let me share my ideas (if he didn't want to hear my point of view, he wouldn't wait to hear what I have to say before shutting down the discussion), but he doesn't want to admit that I am right. Also, when we are talking he says "you're always right". I want to know what he means when he makes both of those statements. I also want to know why he doesn't want to explore topics further after I make my stance known. I do not think lack of respect is the answer because my boyfriend does show that he respects me in other ways. Furthermore, I would like to know how to bring up my point of view and not have him shut down the conversation. Any help would be appreciated!