Physical Attraction?

I have been with my boyfriend for nearly 4 years. The mental attraction to him is thriving, but the physical attraction has completely gone for me. No matter how much we vary things, I find myself cringing every time he propositions me. Does this mean I see him as more of a friend? I don’t want to lose him in my life, but the physical attraction has just gone completely. I don’t know how to talk to him about this without losing him, he’d be crushed.