Hello,
This discharge on your boyfriend’s penis can be due to fungal infection or infections like Chlamydia or gonorrhea which are mainly symptomless in men and may present with discharge from penis. He should get a culture sensitivity of this discharge done to confirm the diagnosis.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
Best thing to do is too see a Doc or Gynae....It could be a STD....and if you both got one you will keep re-infecting each other...
Dont leave it....Both go get checked out.