I'm coming to this thread late, and still reading as well, but this seems to be a good place to jump in and comment. If you both have a Catholic background, and it's not clear if this is still a large part of your lives, then I would suggest finding a faith-based marriage weekend retreat (or longer) that will have a larger than normal emphasis on sex. I went with my wife to one held in Oregon that would meet this description. Naturally, a marriage weekend will cover more than just sex, but some will have sex as a major component and not shy away from discussion and others will downplay its importance. Not sure if there would be a Catholic specific version around, but there might be. Such a weekend may give her an outsider's perspective on why sex is important to you, and if nothing else should give you space and direction to discuss these issues. I cannot say that such weekends have worked miracles in my marriage, which has less sex than yours but more open conversation, but I do see them as helpful. It would be particularly helpful if part of her reluctance to talk about sex comes from any past teaching from the church, because the teachers at at the marriage retreat might be able to ”reprogram" her thoughts in a way that she won't accept from you.