Addictions and Divorce 

This might seem like an ugly word in "polite" conversation, but "addictions" can rear their ugly head within a marriage, and cause a divorce. Since it is such an emotional process of having the person realize that they have this addiction, and that they need to seek help, the family can become completely drained and torn before this occurs.
 
It takes a really strong spouse to stay with someone who has an addiction. The most common addictions are to drugs and alchohol. In these cases, the spouse who has the addiction can be even be violent or untrustworthy.

Loving someone who has an addiction does involve a lot of patience, but also a lot of courage as well. Some spouses will try everything to keep the family together, but if the addicted spouse refuses to believe they have a problem or refuses to seek help, then this could lead the other spouse to quit the relationship. 

It is common to hear from some people who divorced due to a spouse's addiction that their spouse, "loved [insert addiction here] more than them. The spouse without the addiction can often feel that they are competing with whatever is controlling their addicted spouse.