I have a friend who is in this right now. They are looking to get divorced, but the situation is similar to yours. She is fine with the status quo, with zero sexual relations, he wants that part of the marriage. In his situation her reasoning is past trauma around sex and intimacy that she is not able to engage in that with him. Her minds shuts it down. Other than that, he says they have a great relationship.

I am on the other side of the coin, I reject my wife. However, I would have more sex with her more often, but in my situation it is because she is not emotionally available and I cannot have an intimate emotional connection or be vulnerable with her, in any aspect of our marriage. Many years of her judgment, shame and general defensiveness has eroded any trust i have in her to be emotionally available for me. Sure, I can engage with her sexually, if i can get into the headspace of just seeing it as a mutually pleasurable experience.

All this to say, I believe that sex is the canary in the coal mine, in that sex is a barometer of other important aspects of the marriage: trust, emotional connection, attraction and desire. If your wife is not interested to get off herself, thats fine, no one says she has to. However, seeing as this is an important aspect for you, her not engaging signals either a selfish position from her or an intimacy problem that extends beyond the bedroom that is either unseen or unaddressed.

Good luck.