The raise in divorce is definitely in part to the fact that it's more widely accepted - there were many unhappy marriages 30 years ago, but because of religious and social rejection as a result, most women were terrified to leave their abusive or mistreading husbands (and I'm sure there were some men in similar positions). It was highly looked down upon, so people just stayed miserable.
My mother divorced my father when she was 25-26, I was about a year and a half old. She couldn't have made a better move! They're both happily re-married and I've gained two wonderful step parents. I can't imagine how miserable things would've been for me if they had stayed together in an unhappy marriage, they just weren't matching up well.
I know a lot of people like to blame the younger generation for marrying too young, or too fast, but I get the feeling this isn't always the case. There is a percentage of early 20's somethings like myself out there who feel developmentally and responsibly ready for marriage and possibly motherhood. It is certainly not the norm, but that a better percentage of divorces are from 40-somethings women, does say something.
I think a greater portion of women in their 40's are far more independent these days, many women don't desire children like they used to, and don't 'require' a husband for financial aid or support...
But I think caregiver makes a great point, people just don't work at it. Women and men tend to to jump to "well, I don't have to deal with this, I can just get a divorce" more often than before. I wouldn't discount that there are many out there who DO work very hard, but communication is a lost art in this world it seems.
Like Ruth, I've decided to not discuss any issues with friends from this point about my relationships until I've spoken with my SO first. Communication is key if you don't want to build resentment and bitterness - which could only result in something bad anyway. If people take up practicing this lost art, maybe divorce rates could go down? Who knows...