marriage is the social institution under which a man and woman establish their decision to live as husband and wife while friendship is a person attached to another by feelings of affection or personal regard
see it is possible in one sentence
Statistically an increasingly large number of heterosexuals do, and even more homosexuals do.<quoted text>
Marriage is the social institution under which two consenting adults establish their decision to live as spouses.
See, I've made it even better.
As for friendships, you apparently have sex with your friends but the vast majority of us do not.
Always willing to help, Kuntmary.
As to your made up definition of marriage, this question;
If you call the tail on a dog a leg, what is it?
Marriage will always involve a man and woman, bride and groom, and husband and wife.
Oh, and hold the ponderous propensity for children.