A complex issue here.
First, the desire to see (or hear about) a spouse having sex with another partner is not novel. Men wanting to see their wives have sex with other women is a very common fantasy and many do take it to reality. In some cases this is motivated by the husbands hope it will involve (or lead to) his involvement (making it a threesome or otherwise gaining access to sex with the other lady).
However, the fantasy is not limited to that. Many med DO fantasize about their wife having sex with other men. Most never tell the wife about those fantasies and not very many take it beyond fantasy or role playing.
Some people are "compersive" --- a term that most people do not know (even most who experience it don't know this term). Compersion is the enjoyment or happiness one gets from allowing or approving of their partner having sexual pleasures with other people on the basis that they accept that it makes the spouse happy and they want their spouse to be happy. You sound like you might be compersive; however I am not so sure your motivation to want to consider letting your wife have sex with other men is motivated by your loving and altruistic feelings about wanting to make HER happy (although you did say she wants sex all the time and your sexual experiences are limited to 2 women ... making me wonder if your motive is to see her meet her high libido needs and perhaps recognizing your more limited libido and/or limited experience). If the only motivation for the appeal of the idea of her having sex with another man is just erotic for you (to turn you on and for your pleasure) and not motivated and focused on her needs and her happiness, then; technically, that is not technically "compersive." COMPERSION is about caring for what is seen as good for and/or needed by your partner as the primary motivation. If that is a major reason you want like the notion (to allow your wife that extramarital pleasure and to let her enjoy her sex life to a greater extent that simply sex at home, with you) then it is a compersive (unselfish) motivation -- even if you allow it to also be a "turn on' to you. And, it is a turn on for many married men, at least as a fantasy and for some who engage in a compersive sexual lifestyle.
Monogomy is a social dictate and norm (it evolved as a preferance of many early cultures and has been passed down and perpetuated as the "norm" in most .. but not all .. civilizations. It (along with the bible) was fully embrased by the Puritans who came to and founded America. Many customs and norms adopted by societies have some rational reason behind them; in the case of monogomy it is, in theory at least, the manner most likely to keep a mate home, permanently ... and that is clearly the ideal for children (if the parents are decent to their children and for them).
While the vast majority of Americans purport to embrace monogmy and take marriage vows and exchange promises of a monogomus relationship, this is not human instinct but a practical and social distate. [If want to read an objective and good book by two doctors (one M.D., other Ph.D.) on this ... and which examines the general lack of monogomy in the animal world and compares human sexuality, see the book "The Myth of Monogomy").
Jumping from theory to the factual reality of monogmy, its easy to see that it presents a problem for Americans. The facts are there. Over 50% of American marriages now end in divorce; the most common reason given by those who get divorced is "adultery." Thus, while monogomy is still seen as the "norm" and might be best for the longevity of a marriage with children, this "restriction" is often violated. Since we have centuries of conditioning to think monogomy is "the right way" (or even the "only way"), it is not surprising that when it fails, it leads to divorce in many cases. It did not for Bill and Hillary Clinton. It apparently will for the South Carolina Governor, whose wife has filed for divorce now. It appears that Tiger Woods wife is going to try and work it out with Tiger and keep the "nuculear family unit" in tact. With Sen/Presidental candidate Edwards, it seems that they are staying together but she is battling cancer, a higher priority than adultery (I would say). Apparently the wife of former Attorney General and Governor of New York is sticking by her husband after learning that he (a wealth man) spent tens of thousands (or more) on high class prostitutes for years, until caught and made to step down as Govenor. Do you see a trend here? All these men are very powerful, successful and wealthy men in the public eye and with needs to seem to fit the "norm" ... men who can succeed or fail (politicially and financially) by their public images. And all these men violated the vow to monogomous relationships. These are just the ones we all see on tv news. Actually, one recent survey in 07 done of couples married over 20 years, most of those interviewed admitted having an extramarital affair in the first 20 years of marriage (about 63% of wives and about 75% of the husbands ... and research said the gap between women and men who engage in extramarital sex is narrowing with changes in womens roles in society and their presence in the workplace ... creating more opportunities for an affair.)
Well, that should give you food for thought ... and room to think "out of the box" (to look at more than the "norm"). However, I want to end by cautioning you that sometimes what makes for a wonderful fantasy that can spice things up in the bedroom, when you take it to reality it can become explosive. It also does not go as you plan or agree or expect.
You need some serious guidelines and total agreement on all of it ... what you will do and all the conditions and understandings. But, if one likes the "other side" and one does not, there can be a big problem. And its not something you can undo and wipe out of memories if you try it and decide it was a bad idea. Jealously is the major problem with people handling extramarital affairs ... and jealously is one of the worst and most devastating emotions known to mankind (or womenkind). Talk about this long and hard (no pun intended) and be sure it is the right thing for both of you. And both of you need to remember and be minful of one other things besides your sexual pleasures. This marriage, if it fails over going outside the "norm", is not just about the two of you starting over. It's also about that child you have and the impact it will have on the child's future (which also means on your future, as you will always have to deal with and be around each other to be in your childs life, if you split up). Marriages are not always for ever (in fact only 50-50 chance these days) but ... CHILDREN and being their parent is FOREVER! And they have no say in this big decision.
Rob