Often times clients have come to me over the years to report that they have found their soulmates even a twin-flame or two.
My understanding of the twin-flame is that our soul is divided and meets the other half and then comes together as one. The only time I encountered a "twin-flame" in two others the relationship ended in complete disaster, well - save for a good friendship.
Prospective "soulmates" whether karma or otherwise usually feel at home with their prospective life-time other. I ask them about their home life with their family of origin. All the families of origin as reported by clients have had extreme dysfunction sometimes with physical or sexual abuse. That familiarity (root word - family) whether you were miserable with your family of origin or hoped for perfection (on a continuum, of course) is one of the sources of the soulmate stance.
I'm not advising that this is bad, wrong or stupid, rather be prepared to work throiugh your dysfunction as it interacts with theirs.
Ask yourself and your prospective partner after having dated some the following questions:
1. How is your relationship with your opposite sex parent? How is their relationship with their opposite sex parent? [If you were raised by same-sex parents identifying subtle yin (female, receptive) characteristics and yang (male, active) characteristics are important in this exploration.]
2. Are you or they working to move to a more functional / healthy place with said parent.
3. How to you feel about yourself (they about themselves) with regard to your same sex parent?
This will reveal how you and them feel about being male or female and how they will be with you as a long term partner.
If you body is tell you - who you are meant for its likely that biology, sexual drives are the force behind this and is temporary.
Romantic love must be allowed to transform into real long-lasting love. This means work to know who you are as much as knowing your partner.