Bi Have Had The Same Partner For 3 Years And

bi have had the same partner for 3 years and i still get BV. I have never gotten BV until i was with him. His previous partners all got BV so we know it is coming from him."medical history" tells a FALSE story that is doesnt come from the male partner but i beg to differ and do more research on this, especially since 80% of STI's come from the male.
My question, he has been on Metro------- before and it still did not cure. He was put on 800mg of prednisone as a teenager and does not really eat any vegitables. He has a bachelors diet of pizza, beer, sandwiches, sausages, coffee and sugar. Can his diet and jacked up system from the un-necessary childhood prednisone be the reason for BV? Could it be possible that is lives in his system? On his skin, in his cum and saliva??? I need a real honest to god person who is open minded and interested in figuring this out to help us. OR is there no hope and call it a miss match in body chemistry???? please do give some insight, thank you.