HELP ME

Okay, so I've been with my boyfriend for 2 years. I love him more than anything and we are getting married next year. For the last 6 months, or maybe even longer, we haven't been able to have sex. I have no idea why, but I just can't get "in the mood" anymore. And have the time I can't feel anything he's doing to me. It goes numb, or it's like he's just touching my arm or something. Everyone seems to think I'm no longer attracted to him, but I really am. I just really need an explanation or some type of information to explain what's going on. Nothing he does turns me on anymore. I'm getting so stressed out.