I am not a medical professional in any way. However, my husband and both our adult sons are neurodivergent. My husband has always been 'sensitive to spirits'. He felt their presence in certain rooms and he was comforted by spirits of loved ones. This was part of who he was, and was harmless or even enriching to his life.
However, he became very mentally unwell and began experiencing delusions. These were qualitatively very different from his positive 'normal' spiritual experiences.
My eldest son also has had fantastic 'spiritual' experiences which are enhanced by his synaesthesia. However, when he became mentally unwell, he experienced psychosis which was very different from his usual spiritual experiences.
I do not know whether there is a link between neurodivergence and enhanced sensitivity to 'spiritual' phenomena. However, in my experience, people with autism can be very sensitive to atmosphere and very open to atypical experiences or experiences that society has decided are no longer 'acceptable', and they may be very open about these experiences to those they trust.
Voice hearing, for example, is not a mental illness (although it may be a symptom of some mental illnesses), and in some societies, people who can hear voices may be considered blessed in some way. In our society, if someone says they hear voices, we are immediately suspicious of them.
I will conclude my ramble by saying, if you enjoy being with this man, continue being with him. His spirituality and voice hearing (which may just be another way of hearing his internal dialogue) may simply be a positive and rather charming part of who he is. If there is any reason for you to have doubts, then kindly let him go.