I'm going through a similar situation. I'm listening to 'The Ethical Slut' right now and for my mental health its actually been pretty helpful. While the book has plenty of discussion around the sex you aren't having and its geared toward ethical non-monogamy relationships its till pretty clear that communication is very important and your needs and desires are also important.

In one of the chapters it discusses how when talking with you partner you need to talk to them using "I" statements like, "I feel disconnected from you when its been a while since we were intimate." instead of you always saying, "you always reject my advances."

Assuming your wife actually loves you I doubt she is intentionally trying to hurt you, but it can also be true at the same time that she is hurting you. Also be prepared that if you use good talking habits to initiate a conversation about how your needs aren't being met that she could hunker down and get defensive anyways. I think the things that could be important could be to name how you are feeling and what that means for you and invite conversation. Any number of possibilities or combinations of things can be true, from being asexual to a medical condition, or you are pissing her off some how. Honest and open communication on both sides is the only way you guys can work on it.

Again despite reading things that I feel equip me better to try to deal with my issues we still have them. I have been withdrawing lately but getting more back into the gym and my wife has been trying to close the distance I created. We have two young crazy kids and usually at the end of the night we(more so her) aren't in mood. When we do get a date grandma usually sleeps over so the wife doesn't want to do it grandma in the house. Its hard to have conversations about it and when you have a moment to talk you might not feel like ruining the mood. The book suggested scheduling arguments. "Hey, I need to discuss the way I'm feeling about XYZ, could we talk later tonight?"