Necessary? No. Marriage is a life-style choice.
The only things we "need" are (air, water, food, shelter, and clothing). Ironically all of the preceeding can be had in any county jail.
Life however is not just about getting the things that are "necessary". It's about having goals, dreams, and desires. If someone has no desire to be married, have children, or even date then they shouldn't. Life is a personal journey. In a free society you get to (choose) how (you) want to live.