Sex File: He feels more like a housemate than a lover

Suzi Godson: "The gulf between you might have started as a tiny crack which neither of you addressed."

My husband and I had a great sex life when we first met 13 years ago but now feel more like housemates or colleagues. 

I don't doubt he loves me, but I can't remember the last time I felt desired by him, which makes it hard for me to imagine desiring him again either. Is it possible to recover the spark once it's been completely lost?