I have been married (and subsequently divorced) and now live defacto with my partner of 20+ years. So, having done both, I think your view of the benefits of marriage are erroneous.
*I didn't experience an increase in social status when I got married....nor do I feel that I lack it now that I'm simply defacto.
*All those parties you talk about....engagement, wedding, bridal showers etc....they are part of the reason I chose not to marry second time around. They are just parties and have no meaning.
*Damned if I can ever remember an anniversary.
*As defactos we get the same financial benefits as a married couple. (I realise this won't apply to all)
*Not sure how being married helps qualify for a mortgage...my partner would probably qualify more easily without having the other three of us to support!
*The thing about always having someone there to love and support you if you marry....have you not heard of divorce? Marriage is no guarantee that a person will be with you forever.
*Are people really more likely to get promoted at work if they're married? Can you cite evidence for this? I would have thought that the best person for the job is the one who is most promoted.
*Society does not have more respect for a person who is married. We all know married people who are complete assholes and undeserving of any respect. And we all know some amazing single people. Respect comes from behaving in a manner which earns respect...not from simply having a ring on a finger.
None if this is to say that one shouldn't marry. Marriage can be great. But you're giving it far more credence than it deserves.
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.