How do you tell a girl (wife) that she has an unpleasant odor? It hasn't always been that way. For the last 6 months or so, whenever there is penetration, I can smell it without being down there. I just want femal advice on how to break the news.

I'm not a woman but I am brutally honest. Just tell her she smells, wash it dear, you can help her.

All kidding aside it sounds like she has a yeast infection. If she does, you'll need to take the medication also or you will pass it along to others and back to her.

If you can smell it w/out your head being down there, she should be able to smell it too.

If it's been 6 months and she isn't catching wiff of it, I'd say you got two options, smelling salts (on her) or the truth.

Personally, I think you should approach her directly and take the position that you are concerned about her health.  ie...Her Y once smelled like roses but now it's not the same and you are concerned she may have "plumbing" problems. You come off looking like the good guy being concerned about her health and you get rid of the stinkeroo in the process.

If she's worth it, play it off by starting in the shower and YOU wash it for her. If she still smells, it's a good sign that she's got something going on down there. The most tactful way to tell her is to either finger her or go downtown and then come up and put that finger in her mouth or kiss her. If she gets grossed out, then you've delivered the message.

Bring it up. If it is a new development it might be caused by something she may need to be concerned about.

I had the exact same thing happen with a provider once.
I DATY for a good 15min,and didn't smell anything,went to the mish...nothing,went for some doggie and the smell hit me like
a hurricane. It enveloped the entire room (it was a small room.)I could tell that she smelled it to,because she went from having a good time,to completely mortified. I was glad I didn't have to say anything. She was a very sweet girl and I didn't
want to end the session with "oh, by the way,if you couldn't
already tell......."

Sounds like a possible BV infection.  You're not helping her by keeping your feelings to yourself; be honest.  The infection could worsten in time and could create other health issues.