I was living with a girl at the same time my drinking progressed into full blown alcoholism. I would drink a few beers in her presence but hid bottles of vodka which I drank from at any opportunity. I lost interest in sex. I had zero libido and rarely felt the urge. Not even online porn interested me.
Alcohol does suppress testosterone production and if a guy is drinking everyday heavily, over time it can kill the sex drive. I eventually went to rehab and came out feeling like a 16 yr old again. Raging hormones after 2 years of daily vodka drinking.