I had a boyfriend who I thought I was going to spend my life with. It didn't work out, and I'm really glad (though the breakup nearly destroyed me) because he was not right for me at all.
Anyway, all this talk of "When I was 18, I was in love and thought it was forever, and BOY am I glad I didn't marry him!" made me curious....
EDIT: It doesn't count if you're voting at age 18-20 years old. Anyone over age 23 or so who says they're still with their boyfriend from that age should post below so we can gather advice from people who have actually been through it - whether you changed as people, the challenges of being a young couple, if you recommend getting married or waiting, etc.