Your wife needs a better strategy (that doesn't involve insulting you).
John,
Re. the pic: your wife Chris looks good from the neck down. Very attractive... hot, actually. Unfortunately, your photo portrayal of her mostly brings to mind "The Headless Horseman" in Washington Irving's short story, "The Legend of Sleepy Hollow" (1820).
Re.: "...to telling people that I am small at parties."
Sounds like your wife doesn't suffer from excessive subtlety. I suspect the men she talks to at parties have thoughts as follows in response to a statement like that.
1. Men who suspect or know their cocks are smaller than average: "Hm, sounds like she's 'looking,' but if I ask her out and seduce her what would she say about *me* afterwards in public? Forget it."
2. Men with average-size cocks: "Hm, she's obviously 'looking,' but if she doesn't hesitate to say that about her own husband to others, in front of him, would *I* be big enough to meet her standards? If not, what would she say about *me* afterwards, in public? No way."
3. Men with larger-than-average cocks: "Hm, she looks hot and appears to be on the make. But if she would say that about her own husband to others, in front of him, suppose I seduce her and we have an affair — but then later we have a falling out, what would she say about *me* to others? Would she demote me to 'micro-cock' size among other women she talks to? Forget it."
Also, if Chris interacts with and attempts to attract men at parties consisting of co-workers (/colleagues) and/or friends of one or both of you, they may refrain from responding — although they may very well be tempted — because they assume fucking your wife would result in workplace dissension or conflict, which they view as undesirable (of course), or bad feelings between them, you, and your mutual friends.
In other words, your wife may be having problems because she is fishing in "her own pond" or in "your pond."
Your post suggests that your wife needs a better strategy, preferably one that does not involve insulting you, for finding lovers. Enser's suggestions (above) strike me as reasonably good. As he points out, she will probably do better if you assist her in recruiting lovers — i.e., work as a team. To do so would be in the best tradition of marriage — as your wife's husband you are her partner; as such, it is your role (indeed, your duty) to assist her in obtaining what she needs.
I hope this works out well for both of you. Your wife's photo, tantalizingly headless (well, I guess it's tantalizing) though it is, suggests she is a beautiful woman with high potential as a cuckoldress. I strongly suspect that with a better approach involving both of you, you and she can make it happen.
—Custer