Over the past several months, my girlfriend and I have been struggling frustrating problem. I should start off by saying that for the first 6 months of our relationship we had an amazing sex life, with no irritation, rashes, problems, etc. to either of us. However, about 3 months ago there is often an intense burning sensation on penis following sex. This does happen every time we have sex. I am circumcised. My penis continues to burn slightly for a minute or two until the fluids are washed off and I can see red irritated patches of skin.
Would you consider the possibility that she has a condition which is altering the ph of her vaginal secretions, such as yeast infection, or "trich"? You may simply be more sensitive to the presence of the condition than she is now and these can make the secretions acidic or alkaline. So, visiting a gynecologist might prove helpful.