With job benefits, medical benefits, visitation right, taxes and many other advantages stemming from marital status, it can be hard for some types of families to stay together during a move to another state. These families are sometimes denied medical benefits and hospital visitation rights at a time when they may be needed the most, during times of stress and grief. Let this be one less thing they have to worry about.
If you're married in one state, it should not become "unrecognized" or "nullified" by another.