Loss of arousal before sex

I've been in a new relationship for 3 months now. I just went through a divorce, I work two jobs, and I stay up late with my woman. I realize that these are all factors to killing my sex drive. I am taking Viagra which works quite well for the during part. However, I've noticed that for most part of day and night I don't get an erection from anything. Sometimes if the wind is right I guess, but seeing a naked woman like my girlfriend or her giving me oral sex doesn't get me aroused like it should. I want sex everyday and more than once like she does, but I can't explain it. The Urologist said that my blood work came back fine and it's most likely stress, but come on already. A naked woman who wants to have sex with me should make me instantly aroused. Another note. While I was married I had masturbated a lot due to the lack of sex. Every other night I practically did it and using sexual toys at times. I'm not certain, but can I possibly be desensitized to sex? Is there any way to get back that feeling when the very thought of sex comes to my mind that I can be aroused? Please help!