Dealing With New Parent Worrying
First, it is wonderful that you recognized that your wife has changed and want to help her to regain some balance in her life. You don't say how old your son is, so I don't know how long your wife has felt stressed by the responsibility of parenting. The reason I mention this is that we want to consider whether her change is based in the new and additional responsibilities of motherhood or if she may be experiencing hormonal adjustments or post-partum depression, which is common in new mothers and can be helped by psychotherapy and/or medication.
While your concern for your wife is evident, it also seems that, on some level, you believe that she can just change back to who she was. Whether or not your wife is going through post-partum depression, neither she nor what she is experiencing is "ridiculous."
In answer to your question about "what can I do?" I ask another question: In your concern for your relationship, are you asking your wife how you might best participate in the parenting of your child? All three of you constitute the family and a family unit is different from a couple, especially when the third member is a rather helpless one. How creative can you be in finding ways to bond as a family, to enjoy one another and to build on the love that is there?
If you are having difficulty communicating with each other in a helpful way, perhaps some sessions with a couples' counselor or a counselor specializing in dealing with families with new babies can be beneficial. Although it does not seem so, your son will grow up very quickly, and all the stages of his life and your life as a family are precious.