The Huffington Post reports on a study here showing that the more education you have, the less likely you are to get divorced, unless you are an African-American woman. Their divorce rate is still high, although it may be because they are less likely to be married to a man of similar high educational achievement.
It does make sense that money can cushion against family troubles. However, I think it is equally possible that the same strengths that enable people to get college degrees also help people sustain marriages—the ability to work hard, to think clearly, to carry out long-term projects, and to read and write well. All marriages have problems, and the intellectual and personal abilities necessary for college completion also help with the day-to-day issues that come up in any marriage.