I was one of those with a 'shotgun' wedding even in 1964 .. just about made it, but didn't have to. My Mum and Dad said would support me if I decided against it.. but I didn't. Even though I am divorced, was married for 24 years, so didn't do too badly.
Lots of my friends and associates live together now rather than marry, which is considered OK by today's standards and yes, that's fine. I hate the word 'partner' though.
Don't think I would have ever done it, (never say never though, eh ?
) but not from a moralistic point of view, just think what's the point ? Might as well be married. Good to still have your space and not have the bother of pandering to another person's needs, like the cooking, washing, worry of heavier bills, etc. Stay with your Mum and Dad, and still see your girl/boy-friend.