Well, first the need to marry is about loving one another and comittment. But equally as importantly it is about being able to be there for the person you love. For example, even finding out what is going on for your loved one who is in the hospital is impossible if you are not a direct relative, much less making decisions for them when they are not able to do so. Then there is joint tax returns, wills which are often not honored by courts if the life partner is of the same sex. And yes.. Divorces are bound to occur, but nobody is protected under marital laws. For example, I own my home... I tell my partner who contributed equally for 20 years to take a hike... I don't compensate her... As the laws have been, she just has to bite it and move along, as she is not awarded the same protections married couples are.

As far as getting married for the sole purpose of having children, as you stated; If this premise is true, should you not void all marriages whereas one or the other cannot have children? We both know that is not realistic because getting married is not just about having children.