Bigger isn't always better. I find oral sex much easier to perform on a less well endowed man. I find him less intimidating as well. Less intimidation leads to better sex in my case. A woman's vagina has majority of the sensation in the first 2 inches. That is where majority of the nerve endings are.

I agree w/ Hamster, did your wife just come out and say "I'm leaving for a guy with a bigger penis, and even if she did say that, who to say she didn't say it just to be mean.