marriage vs not

An
My partner and I were having a conversation about marriage and he thinks those who have the title as husband and wife are taken more seriously than those who are just boyfriend and girlfriend. I told him that it's just a title and one that doesn't hold THAT much meaning to me because I don't care what other people think. I told him there can be a couple who are not married but have been together for 7 years and love each other way more than the couple that just got married after 1 year. So why should the married couple be taken more seriously than the non married? He said its more than just a title and you're more committed so people will take you more seriously. I see where he's coming from and I do think that people feel this way in general, but why? Why does husband and wife get more respect than the boyfriend and girlfriend who've been dating forever? Thoughts?