The urethra and bladder are sterile environments. And if any bacteria
/virus/foreign substance is introduced into the urethra, an infection can occur. Also, the discharge you are seeing can indicate an std or other infection.
Blood in urine
could occur as a result of trauma or a medical condition. Throughout the genitilia, there are many areas and blood vessels that could be broken, leading to blood in the urine or semen
Items that could cause trauma and blood in the urine could be aggressive sex
or masterbation, interrupted sex, kidney stones, prostatitis
or a procedural biopsy on the testicles/kidney/bladder.
Medical conditions that can cause blood in the urine include: side effects of blood thinners
, stds such as chlamydia/genital herpes
, prostate cancer
or bladder cancer
Since this is an ongoing condition for your boyfriend, it is suggested that he see his doctor to determine what the cause is. If there is an infection or trauma going on, it is important to get it assessed.