Hi Crimson, Not sure if the following will help you at all, but I have been reading a book on mlc that clarified a lot of what my H is doing.
The argument is that our spouses are going through a process similar to 'mourning' or 'grieving' (their loss of identity, sense of immortality, sense of meaning in life).
This grieving often involves a stage in which they say to themselves "if only".
In your case, you might see your W as saying: 'If only I had had another child". "Then perhaps I wouldn't feel so bad".
It's a way of seeking relief from the inner sense of despair. A way of trying to point the way forward.
It's a fantasy (at this stage, because D is still on the agenda for her) but it reveals a lot about the inner needs of the person who is expressing it.
The writer of the book says that the fantasies mlc-ers typically engage in (men often say they would like to be farmers, helpers, nurserymen or writers) are key to the modification that is required post-crisis. The meaning of the fantasy needs to be explored by the person -why do I want this and what is lacking in my inner life/relationship.
The takeaway message, I suppose is, again, that such things need to be talked about. The meaning of this desire for IVF by your wife might well be something that should be explored in counselling.
Again, apologies if I come across as an amateur analyst here. Not trying for that, just thought it might help you deal with the apparent incongruence of her actions.