There is no question about it: marriage adds burdens to our lives. It also adds comforts and joys. When the burdens outweigh the other two, it's time to try something different.
In my blog, I often suggest three things you can do when you feel overly burdened: (1) Assume Love, (2) Expect Love, and (3) Find Third Alternatives. I have found that all three can evaporate some of the burdens of marriage. They can do so very quickly and very dramatically.
There are other burdens they won't help with, burdens you can do little about except volunteer to carry them in hope of a better tomorrow. Big among them are a personality disorder, an addiction, a chronic medical condition, or a chronic mental health problem that prevents your spouse from acting on his or her loving thoughts toward you. I recommend you do everything necessary to protect yourself, your children, and your spouse's conscience from the consequences of this loss of self-control, including setting a time limit on accepting any effective, safe treatment that is available.
There are other situations over which you have very little say, too. Your spouse, for reasonable or childish reasons, may decide to stop making any attempt to love you or even to stop living with you. He or she may decide it's OK to take a lover, multiple lovers, or even a second wife. Some couples manage to increase the comforts and joys to match the extra burdens, but not many.
No one else can decide for you how much added burden you can or should handle. Unless your country or your faith prohibits it, I find it perfectly reasonable to divorce to put an end to excessive burden. Personally, I prefer to see someone divorce rather than remain in conflict or avoidance or depression for years.
So, let's pay attention to the difference between burdens we can do nothing about (like addiction) and those we can fix (like messy houses, angry family gatherings, too many chores, and insufficient sex) and see if we can help some of you avoid divorce without looking down our noses at those who choose it when the burdens grow too heavy.