Aregente Noir:
...cultivate feelings of loving kindness and internally repeat Metta phrases directed towards my husband. Anyone else do something similar?
Sex is only pleasurable when there is complete letting go, physically and emotionally.
In French, the word for orgasm is 'petit mort' (little death), because it's a little taste of ego death. Death is about letting go. Meditation is also about letting go.
Letting go is not possible whilst you are repeating phrases to yourself. It's almost the opposite of letting go.
Maybe it's a physical or hormonal thing that has caused the disinterest. If that's the case I suppose the best thing is to see a doctor. If not, then you could try getting in touch with your inner vixen. Relax the body, have a drink or two, dress up, get down, talk dirty, tell him what you want and really let go. Far greater intimacy will be achieved.