a "sole mate" is someone who understands your feelings well, and you two care a lot about each other. But you two may or may not get married eventually =知己/知心人/知音人
匿名君, I guess you are talking about “soul mate”.(不是sole mate或蘇眉,哈哈) A soulmate or soul mate心靈伴侶 is a person with whom one has a feeling of deep and natural affinity, love, intimacy, sexuality, spirituality, and/or compatibility.