Just about everyone -- a man as much as a woman -- is rendered more mature and wiser after marrying. This is not an insult to singles. It was as true of me as of anyone else. If you're single, ask any married person -- happily or unhappily married -- whether or not marriage has matured them.
The single biggest change induced by marriage is that you can no longer think only about yourself. "I" becomes "we." Narcissism becomes far less possible in marriage than in the single state. And just as marriage decreases narcissism, it increases wisdom. Having to relate to another human being (especially of the opposite sex) to whom you have made a lifelong commitment (even if it ends in divorce) vastly increases your wisdom. And if you have children, your wisdom increases exponentially. Again, ask any parent if they are wiser since becoming a parent.
Am I implying that increasing one's maturity and wisdom works in favor of the Republicans and against liberalism and the Democrats? Absolutely. Wisdom and contemporary liberalism are in conflict. That is why the vast majority of people who change their politics as they get older (and presumably wiser) change them from liberal to conservative.
For all these reasons, the Democrats know how important it is for them to expand dependency on government and to promote "alternative families" rather than the family that consists of a married man and woman with children.
The Democrats know where their votes are.