I wonder why you have not persisted with the issue of sexuality in your couples therapy sessions? Sex is often an expression of your entire relationship and should not be ignored in the therapeutic environment. It can be difficult to bring up and discuss, but clearly you have strong feelings about the lack of intimacy, and are obviously sad and imbued with longing. If you do not give space to this great sense of loss and shame you are feeling, you are condemning yourself to continue in quiet desperation, and threatening the longevity of your marriage. You deserve to be heard.