Loner
A loner is a person described as not seeking out, actively avoiding, or failing to maintain  interpersonal relationships. There are many potential causes for this solitude. Intentional causes include introversion, mysticism, spirituality, religion, or personal considerations. Unintentional causes involve high sensitivity or shyness. Multiple reported types of loners exist, and individuals meeting the criteria for being called loners often practice social interactions with other individuals while displaying a variable degree of introversion leading them to seek out periodic solitude.