Getting married when you already have children from a previous relationship can oftentimes be a challenge. In many people's lives, they find a significant other who accepts and loves their children as though they are their own. It's a beautiful thing when families blend together seamlessly and work out for the better. However, this is not the case for every family.
Some families have a hard time accepting other children who are not "blood-related" to them or biologically theirs. Sometimes, it is not the spouse that has a hard time, but their extended family who will not be understanding or accepting. This, of course, can cause issues in the relationship overall.