Even the most expressive men have moments when they do not feel like talking to anyone, and yes that includes his girl friend. So what are some of the possible reasons why he is not talking? I list some of the reasons I often observed.
He is not talking because he is feeling guilty. Women are smart and guys really know it. When your man has committed a minor offense like casually receiving and sending email to an ex, he may get quiet moments in order to avoid incriminating himself. A guy friend often tells me that after going to bars and lying to his wife, he often stared at the television all night because he is scared that he would let something slip in his mouth accidentally. But no worries, the occasional silence of this kind is usually indicative of a small fault, something that is not relationship threatening type. However, when the mum moments are becoming more often, then that's a different story.
He is not talking because he just simply wants to quiet down. Harping on the high-calorie count of your dinner or blurting out loud why some girls are not right for you brother are things that men really do not care about. Thus, their ways of staying away from that conversation is to just calm up ourselves. A friend told me when his girlfriend steers him up into conversational black hole, he stays quiet as a way of letting her know that he is not interested with what she is talking about. It took her a while, my friend narrates, for her girl friend to notice but now she knows his signal of disinterest.
Lastly, he is not talking because he had a hard day. Put simply: If his day sucked, he is not going to feel kike rehashing the whole thing and tell you all the gory details of his not so good day. Men, unlike women, like to keep quiet after a not-so-good day. Women on the other hand, sort of find a relief when she blurts those things out in her system. Girls feel better venting even over the smallest things, but guys are different, they do not want to vent, or at least for that day. A friend told me that whenever he sits down to have a dinner and mutely stare at the menu, his girl friend figured out that it is not personal, and thus, she waits it out. Halfway through the meal, my friend starts to feel like himself again and that is the time when he will be able to talk about what happened or just direct conversations over lighter subjects.
There is really nothing to fret about to your guys being on his mute mode, just like girls, guys wants and would like to have their quiet moments, those moments that they just sit there like a zombie and having deep thoughts. So just give them those moments, do not be paranoid and think it's because of something you did or failed to do. Almost always, it is not personal, so do not fret.