While I do believe that God presents people to us (plural) I don't believe in "soul mates", people destined to be our spouses. I believes that He presents MANY people to us to fellowship with not necessarily marry. That's our choice to make. He does this when we're in line with His will and have had quite a few experiences with Him, after we've been obedient to His will not just because we've been praying for one.
The bible says that we can marry who we want to as long as it in the Lord, a converted Christian.
To marry or not to marry is our choice. Paul said if you CHOOSE to marry you're not sinning and if you CHOOSE NOT to marry you're not sinning.
I think we need to careful when attributing our relationships to God just because we're happy for the moment. If and when they end badly, we tend to blame the Lord for sending that person to us, for not warning us or beg for the return of the person and look like fools to others in the process. Every good gift comes from above (paraphrasing). If there's a lot of drama attached to it(pre-marriage) it's not from Him. We have to remember that the devil is a counterfitter, he gives gifts too but to weaken us and to destroy us in the end. AND He'll send us someone who LOOKS like a saint, the answer to our prayers but one who does not have our best interests at heart at all.
We are not obligated to stay in any relationship pre-marriage and we need to remember that the other party is under absolutely no obligation to remain either and can end it at any time. So it's best not to get wrapped up emotionally with someone we're not married to. If they dump us they have the freedom to do so.
God will not bless our mess! If He tells us not to marry and we marry anyway then we will receive His chastisement not His blessings. He does not reward disobedience. While we are still bound to that person we will have to endure what He tried to save us from and He will strengthen us to do it. If we marry before knowing the Lord to someone He would not have approved of after conversion, in that situation I believe He will bless the marriage because He is a forgiving God. He frees us of our sins that we committed before salvation but He says we're accountable for those we commit after receiving salvation.