It's a tough situation.

Some parents may not like to express it but there is always grief having a child that differs from their set of expectations - be it in terms of gender, sexuality, choice of profession etc. It seems your wife is grieving the fact that her daughter is neurodivergent. This is now compounded by your daughter's choice of partner which will further make life harder (e.g. acceptance, judgment, discrimination, or being the caregiver). I think your wife needs support, education, compassion... to allow her to grieve the 'death' of that imaginary child she had in her mind.

It is tough to be 'different' in today's society and it usually comes at a heavy price. Your wife does not want her daughter to struggle more.

I, personally, would be more concerned about the 'schizophrenia' diagnosis. As in, how well is it managed and impact on your daughter (yes, potentially being partner's caregiver)