The pains and discharge from your urethra
can be a indication of some infection and the same can be commented on only after an lab examination of your urine and semen. Not having multiple sexual partners makes you less likely to have a sexual infection, but doesnt make you immune. Your concerns towards your wife are genuine and understandable. There are some tests that you can get done for your wife aswell like TORCH which will reduce your anxiety
Thanks for giving an opportunity to help you!