I read Mayim Bialik's book on attachment parenting just recently. Yesterday I saw that she and her husband are getting divorced.
really, really bad. This is true even in the best case scenario (where the parents get along well, live close to each other and provide a stable situation post-divorce).
Of course, some situations do require drastic action (for instance, untreated mental illness, addiction or unceasing violent conflict, whether verbal or physical). But I doubt this is the case for Bialik, since she is asking for joint custody (meaning she considers her husband reliable enough to be solely responsible for their small children). Plus, in her book (written this year!) she goes on and on about how gentle, considerate, and responsible her husband is (of course, it could be all lies but let's assume not). Whatever is wrong, it's not due to serious character defects of the type that merit divorce.
Marriage is about a lot of things: love, companionship, finances, an efficient division of labor...But one of its main purposes is to provide a stable environment for children. Children in other societies thrive without securely married parents, but that's because those societies are very different from our own (usually the children are embedded in a secure framework of extended family, where the role of parents in raising children is relatively much less important). In modern America, providing your children with the best environment and upbringing means providing them with married parents. (For example, virtually all students at top universities have married parents, even though half the population has divorced parents.)
In other words, being a good parent generally means staying married. The ability to create and maintain a happy intimate relationship is actually the most important parenting decision you will ever make. Bialik obviously cares deeply about being a good parent: but she is investing her efforts in the wrong areas (homeschooling, for instance), and as a result is having a massive parenting fail.