I am one of the few imperfect ones.
Being a mom can take a lot out of you and sometimes there isn't much left over for your husband. I have been there. And back. And there and back. It's easy to put motherhood first because kids are young and need you in a very different way than your husband needs you (or you need him). We are adults, we can handle things on our own if need be. Kids actually, literally need you. For everything. People can preach and hold themselves to the high standard of balancing both perfectly and maybe they can do it, but I think it is HARD. And all too often the marriage comes in second.
I am very lucky to be married to a man who is patient and understanding, and seems to get this. He is also pretty independant and not at all needy, which helps A LOT. He takes being a dad as seriously as I take being a mom but we both value the marriage. We work at it. We fail sometimes, but we work at it. It's getting easier now that the kids are older. They need us less so we have more time to give to each other. It's kind of a fun, exciting stage.
I do think I put motherhood first for a lot of years but I don't think it hurt my marriage. My husband and I both have viewed this time when the kids come first as temporary. We know it isn't forever. We never ignored each other but there were times when we probably could have given each other more. But luckily we have the same level of commitment to this life and we just keep working on it. We have learned from it and try to be better. What more can two imperfect people do?