You "sometimes hear that people have turned while on PrEP" because the tiny number of cases (2 or 3) have been blown way the fuck out of proportion by anti-PrEP fanatics. The stuff works, really well, if you take it every day. Better than condoms. (You don't see headlines every time someone gets HIV while using a condom -- and that happens every fucking day).
Take the pill religiously and go to your doctor every three months as required, and rest assured that you're more likely to win the PowerBall than to get HIV.
However, if you start having more raw sex than before, the tradeoff will be a higher risk of STDs. Get tested often (quarterly is best). And be honest with your wife about that risk. You are protected against HIV, and the others are curable (or, in the case of herpes, also blown way out of proportion by scaremongers).
Three more tips: (1) Have a good long gargle with antiseptic mouthwash (like Listerine), deep in your throat, after sucking cock. You can get STDs down there and this helps kill them. (2) Try to piss after fucking raw. Helps clean bacteria out of your dick. (No guarantees, it's folk wisdom, but it seems to work for me). (3) DON'T douche after getting fucked. Contrary to what some people think, it doesn't prevent infections -- it can irritate your rectal tissue and make infections MORE likely. If you want to douche BEFORE getting fucked, do so early, and give your hole a couple of hours to recover from irritation.