why cannot women have both?

Why cannot women have both, a moderately successful career and a family? I am single, also working on my PhD. I am starting to think about this issue. My boyfriend totally supports my career choice. He is asking around about good universities in his preferred areas. We actually joked about career women the other day. I pointed out his mom is a career women with master's degree. He said that his mom did not work when he was a baby. I complained, that I cannot waste years of education for nothing. He just laughed. I don't think he wants me to be a housewife. I do agree that a woman's primary responsibility is to raise a family. There must be some way to work out both. One thing for sure is that I have to quit spending so much time on line.