If she's talking to you about it that's a good thing. It does sound like you're a bit lacking in confidence and to be honest with you if your wife is attractive enough to get attention, she'll get it with or without the bolt-ons. If your insecure about it then tell her. Chances are your insecurities is why she feels the need to get your approval.
My wife got some and I like them. Yes, she does get looks, but it has done nothing but enhance our sex life. She feels better about herself, sexier, and is more confident. There's a reason guys call them fun-bags.
If your having a rough ride in your relationship then these won't fix it, and the additional attention she'll get , and confidence gained will enable her to leave. It is interesting how many women plan out their exit far in advance to include plastic surgery, new cars, etc. If she's planning her exit you should be well aware of it unless you're blind.
Only you know what's really going on. Are you insecure and creating a problem or is there a problem already?
Boob jobs are so common that it really isn't as big a deal as you're thinking it is.