Get a copy of John Grey's book Men Are From Mars, Women Are From Venus. He deals with this very clearly. It's called going in to his cave. Most men are internal processors, they have to withdraw and think things out, women who are verbal processors and tend talk through things have a hard time with this. Grey explains how to work with it and also how to get him to accept listening when you need to talk. This is just how men are, it's wired into them, in telling you that he needs this down time, he is doing what he should, when that happens you need to accppt that he isn't rejecting you and he will be 'back'. Call a couple girlfriends to meet for lunch, take some good walks, go work out, take care of a project, paint your nails or color your hair - do some things that don't need his participation and keep you feeling good.