I've been married for 14 years so I feel qualified to answer this. It did not hit me that my wife was the one until about 6 months into the relationship. I was a military man so my future went were my company went. I got married in my early 20's so I don't think I was the one who had doubt.
My wife seemed to drag feet a bit out of fear of her parents reaction. It got to the point were I asked my wife 3x to marry me. Out of fear she could not say "YES".
I got so fed up that I told her I will never ask her again. And if she wanted to get married she would be the one asking me...
Well about 30 days later after I left to visit home on leave, when she picked me up at the airport she could not hold back and asked me. I knew the reason why she was reluctant to say yes when I asked, It was not that we were not meant for each other.
She was scared her parents would kill her. But after 14 years of marriage neither of us regret our decision.