nearly everyone you talk to dislikes large government ... and is opposed to gay marriage.
Can you explain how a smaller government would deign to determine who marries who?
Gay marriage would increase the government benefits available to gay couples including tax breaks, government subsidies, social security benefits, free military housing, green cards, health insurance, etc.
Gay marriage is not just a symbolic gesture, it will increase government spending to comply with laws and subsidies to make them available to gay couples.
Gay couples admit that they want these government subsidies, instead of living as roommates or single people.