It is immensely frustrating when your partner won't talk to you, and in the long term it can undermine your communication and your relationship. There are many reasons for a refusal to talk, and understanding some of them can help you encourage your partner to open up in a gentle and non-judgmental fashion.
If your partner grew up in a home where there was a lot of open conflict, she may employ conflict avoidance tactics as an adult. This means that she will avoid open confrontation and conflict with you, and instead will bottle up grievances and avoid discussing problems. As a result, grievances and concerns may be referred to only through sniping and bickering about unrelated topics. Conflict avoidance can be damaging to a relationship.
If your partner refuses to talk to you and withdraws into himself yet refuses to admit anything is wrong, he may be a sulker. Sulking is a form of conflict avoidance and is particularly common in those who lack good communication skills or the ability to self-assert. Sulking is also used as a way for your partner to draw attention to himself and his unhappiness without talking.
If your partner has experienced a traumatic event in her past, this may lead her to be withdrawn and feel emotionally numb, causing her to avoid meaningful communication. Detachment from others is a hallmark of post-traumatic stress disorder. If your partner has experienced trauma, a therapist trained in trauma resolution can help your partner process the event and no longer react to stimuli that reminds her of the negative experience.
Your Response to a Non-Talker
How you handle a non-talking partner can having a lasting impact on your relationship. If your partner stopped talking because of a conflict, give him time to calm down. Once a person is flooded with adrenaline and other stress chemicals, it can be difficult to think clearly, so stonewalling -- not talking, can be a self-management technique. Once things have simmered down, ask him what he expects from you when he doesn't talk. Let him know how this avoidant behavior makes you feel, and tell him that you want to work with him to develop a more positive way of handling conflicts. During this conversation, listen attentively and ask questions for clarity. Avoid criticizing, which will probably lead to more stoney silence.