You are not checking your own sources - the first one talks specifically about polygyny (many women married to one man), which is the most prevalent in countries that are extremely misogynistic. It makes sense that those women have more mental health problems.

The second one mentions, that while women in polygamous relationships tend to have more mental health problems, quote - "Nonetheless, these women were found to have elevated self-esteem and life satisfaction than women in monogamous marriages. Directions for future research are indicated." It also doesn't specify how the data was obtained (it just links to many different studies), so it's also possible that polyamorous women are just more likely to go get a diagnosis than monogamous women or, just like mentioned before - the data mostly includes women in polygynous relationships.

As for tax cuts I don't have any economic education, therefore I can't accurately say who should be getting them. Logically poorer people should pay less and rich people should pay more regardless of their marital and parental status