When two soul mates meet, they become bound to one another. It's not like marriage. When two people are bound, they're bound for life. A two day ritual takes place wherein the two people swap stories, secrets, and in some cases, blood. This is all done in secret. No one other than the two people can know the things that are said.
Some people are so in love when they meet that they decided to swap blood. When this happens all living family of the two soul mates must attend. A preacher and the soul mates stand at an alter. The preacher cuts both of the people's hands and holds them together in his hands. This is the first part of the ritual. From there the second part of the ritual starts. The soul mates hide away for two days and spend all of that time simply talking to each other.
At the end of the two days everybody comes back together for the third part of the binding process. The preacher repeats the blood binding process and the two soul mates are bound.