Listen closely to your wife - it may not be a size issue. She may (in blunt terms) simply want more cocks. i.e., sex with more men, - not you. She's not thinking about ending the marriage, - she's thinking about how she can get laid more often. When she finds a man who is attractive, nicely equipped and personable, she'll subtly let him know she's interested. Especially if you aren't taking good care of her in the bedroom (how's your lovemaking skills?), cumming too quickly, not giving her oral, withdrawing and going to ...... immediately after that last little spurt is out, etc. Even if you are a skilled lovemaker, she may still want more sex. Women have much higher thresholds than us guys do.