I would imagine that a heavy work schedule that conflicts with that of your significant other or leaves one of you in charge of ALL the household and family duties might contribute to divorce in a marriage that is already troubled, but I don't see it would actually cause a divorce in a good marriage.
Unfortunately, in this economy, it is not uncommon for one or both partners to work long hours (to keep their job) or to work more than one job so that there is enough money to pay all the bills. In a good marriage I think that the couple understands that the sacrifice of time together is for the good of the unit and that the partners learn to make the most of the time they do have together.
For six years, my husband and I each worked one full-time job and one part-time job. It wasn't easy and we missed each other's company frequently, but it didn't cause a break-up. We were understanding of each other and the common goal. We were not young - maybe maturity helped us through.
I do agree with nightwork4 and editor that for many of us the extra work is due to the greed of our personal desires. I admit that it contributed to our reasons for working so much - we wanted to buy 10 acres of mountain property for retirement without giving up anything we already had. For us it was worth it - I get to retire in 3 months and we are planning to move to the mountains next spring :)