Yes in a way you are right. AND if the Affair never happened and she just started lacking the desire I would be more understanding. BUT the fact that the last person she did have / want to have sex with was the OM after 20 years marriage to me..... I do find that hard to accept.
Don't worry... this is progress I will soon have her at least back on MY bed.
And if I claim to be a wise man, well It surely means that I don't know