I went thru this same thing when I was married to my ex. Towards the end of the marriage my sex drive was nil... and I was pretty concerned. Enough so, that like you I spoke to the doctor about it.

bcipam is right. What actually happened is that the emotional connection between us was nil, so in turn the physical connection was as well.

since then, I find myself single... and believe me, the sex drive is there. The thing with ANY relationship is that they take work to keep alive. I know lots of men who are very good people that I don't want to have sex with... but that was not an issue with you and the BF... so take some time to think about HOW to renew the emotional connect... and then put some effort into seeing if that helps... things as little as picnicking at the park can do the trick. Get away once a week from the tedium of life... paying bills, shopping, laundry, and TV are NOT romantic and do not connect most people emotionally.

Hope things work out well for you... hugs...