When my wife worked, she missed our kids tremendously. Almost 75% of her take home went to day care. She was pretty miserable.
Now she stays home. She gets a lot of off-hand comments from other friends with kids about "how bored they would be if they stayed home". Or from friends without kids about "how they feel like they are doing something with their lives".
Now she feels like she isn't doing enough with her life.
Maybe she needs thicker skin, or maybe the societal pressure for women is immense.
Men working is expected by society. IME, the dads I know who stay home get more of an "awesome bro!" type response when they say they stay home.
I just feel like no matter what I do, I will feel happy with kids. No matter what my wife does, she feels like it isn't good enough.
[Edit: so many links to books! I've exhausted my audible credits for the month. Thanks for the support!]