I'm afraid it's me, Dr José, once again!
NSU can be caused by lots of things, not always by infection, and vigorous sex can be one. The urethra is very sensitive and irritation can remain there for quite some time. If there was inflammation in the urethra, the acidity of the urine itself can cause this symptoms, without necessarily having an infection. If you have been tested for all possible STDs and all the tests were negative, and in addition you have been treated with the appropriate antibiotics, we cna conclude with confidence that you are not carrying an infection and that it would be safe for you to have sex with your wife.
i have had a similar experience. NSU detected but all tests came back negative. used Azitromycine (precautionary) and metronidazole (cos a partner said she had Trichonomas). Had discomfort at the tip of my penis for a couple of weeks which sudsided. further tests revealed no NSU and urine test was negative also. a day ago i noticed some fungal growth. could this be the Trichonomas returning? maybe the infection hasnt fully cleared up. I havent had sex since my results (4 weeks or so).