Here's my advice, for what it's worth. I would not compare your wife's desire for you with her desire for her affair partners. Affairs are exciting, short-term relationships in which sexual desire is at its peak. Sexual desire in the context of a long-term relationship will never be the same as it is in the context of an affair. So comparisons are pointless.
Now on to you. The reality for you at this point is that your wife does not sexually desire you much, if at all, and hasn't for a long time. That's a painful truth, but you have to accept it you want to move forward. I strongly reocmmend that you not try to figure out the reasons for her lack of sexual desire, let alone try to fix her (or push her to fix herself). Just let her know very clearly how you feel about it. Also, if you have a boundary (such as that you will not stay married for longer than X number of months if things don't improve), let her know that, too. Then leave the rest up to her. Either she will change or not. You can't change her.
