“Last night I dreamt that somebody loved me,
No hope no harm, just another false alarm.”
-The Smiths, Last Night I Dreamt
The idea that there is 'the right one' is more Hollywood than Holy Word. It's also Hollywood to believe you need to be married or romantically involved to be happy. Our master, Jesus was single. His greatest apostle, Paul, was also single and he was thankful for it. As one celibate preacher once told me, 'I'd rather be a bachelor than wish I was.'
But if you are a single Christian who aspires to get married, then you need to be rid of the silly notion that there is one special person who God has designed just for you. The Bible says the opposite. The one requirement for a spouse which Scripture gives is that the person you marry needs to be someone of the opposite gender who is a fellow believer. (1 Corinthians 7.39). Within that framework, you're free to marry whoever.
If you follow Jesus then there are probably many people of you could be happily married to. Fretting about whether a certain Christian is "the right one" is a waste of time. There is no perfect mate and there will always be some degree of incompatibility because we are all broken people.
I'm not suggesting that you marry the first available person who says they're a Christian. Just because you are 'permitted' to choose from among the many, doesn’t mean that everyone is an equally wise choice. Is the person an idiot? Is he selfish? Is she moody? A lunatic? Getting advice from mature and honest friends about a potential mate is also helpful. This helps you to see the other person's shortcomings that we can be blind to if we've fallen in love - and are therefore partially brain dead.
One final hint: if you do decide that marriage is for you, then look for someone who is considerate of other's needs. It is the most underrated and underlooked for virtue out there when it comes to finding a spouse.