I'm in a happy marriage, so yes, they exist.
I guess my question to you would be, why are you attracting the same type of person? You do notice a pattern here, don't you? You attracted the same guy all three times, and there's something wrong with that.
Get out of your comfort bubble and date someone that you wouldn't think you could date in the first place. I thought I was meant for the weepy artist type; the bad boys that you couldn't take home to mom; the type that worshiped music, was soft spoken; the introverts. I got out of the pattern because they were all LAME and not the kind of guy for me.
So why did I end up marrying the all-American jock, boy next door, could totally take home to your mom, barbecuing, beer guzzling MAN? Because he was for me, and that was it. Pattern broken. And I've never been happier.