Reduced Sensitivity

Years ago, when my DW cupped my balls and gently rolled them around in her hand, it gave me waves of pleasure that spread throughout my body. It was very relaxing, but not sexually stimulating and it didn’t go beyond the p-wave stage. In hind-site, that must have been from indirect prostate stimulation. About 10 years ago, the p-waves stopped when she would do that. It is still enjoyable, but not to nearly the same level. Has anyone experienced an apparent reduction in sensitivity? If so, have you found a way to restore it? I think that a direct p massage would be greatly enhanced given how good the indirect felt.
Earl