Well I can't speak of soul mates, cus it really doesn't matter to me if we have or not. But with reference to Paul, I think context is important. Paul discouraged marriage at the time of when was writing the letter to Corinth, because he believed that Jesus' return would be in their lifetime. To remain as you are (wed or unwed; uncircumcised or circumcised; slave or free), for the present world is passing away (1 Corinthians 7:17; 21; 26-31).
If someone was thinking of getting married Paul was concerned that they 'their interests would be divided' (1 Corinthians 7:34) In his letter, he didn't want to restrain them from marrying, but to be secure in their devotion to the Lord. If a person could not control themselves, then it would be best that they marry. It appears to me, his stance of marriage is based on the belief that Jesus would return soon, and because there is no marriage in Heaven, why focus on that when the time is so short on earth.