Apples, are you 100% certain your wife is not having an emotional or physical affair? Some of the circumstances you describe -- sudden change in intimacy level for no apparent reason, long stretches of time away from home, refusal to talk about the relationship or what's wrong with it -- suggest she might be. If she is having an affair, any and all attempts to work ont he marriage are likely to prove useless. It's something you need to rule out before going forward.
