Twin Flames and Soulmates
Twin flames, also called twin souls, are literally the other half of our soul. We each have only one twin, and generally after being split the two went their separate ways, incarnating over and over to gather human experience before coming back together. Ideally, this happens in both of their last lifetimes on the planet so they can ascend together. So you probably haven't had many lifetimes with your twin.
Each twin is a complete soul, not half a soul. It is their task to become more whole, balancing their female and male sides, and ideally become enlightened, before reuniting with their twin. This reunion is of two complete and whole beings. All other relationships through all our lives could be said to be "practice" for the twin, the ultimate relationship.
In the video below, LIORA is speaking about the most Frequently Asked Questions of Twin Flames.