Libido and sexual desire changes

Patient: Dear Doctor!I have been experiencing some trouble with my libido for a while now. My sexual desire seems to change very quickly, like one day i find it hard to maintain or get an erection on the other day i got one like every hour. For example on some days i couldn’t even have sex with my girlfriend, the other day i just saw a random girl’s waist and it turned me on (i found my girlfriend desirable).I checked my testosterone, prostate, blood cholesterol, blood sugar which are all fine, my blood pressure is rather low, i do sports 4 times a week, i’m not fat, i’m not using any kind of drug, not a smoker, don’t drink alcohol.This really bothers me, and the only connection between my lifestyle and libido is that i used to be overweight, that time i had higher blood pressure, I always was horny but i don’t know if there is really any connection between the two.Thank you for your answer.