Although this is a hard question i will try to answer (as my hobby anyway)
Sometimes, you may have a strong feeling for emotional comfort, or you may feel something i like to call a "Destiny Presence"
Belive me, i wished for someone as "The One" for myself, and i got it! (almost, we're getting there)
There is no "one", a successful relationship is created out of hard work and commitment, not luck.