Initially one loves another out of a delusional belief that they fulfilled and completed them. Love can emerge from this madness. Over time, if one is mature enough, they come to recognize their differences and see that they complimented each other. We all have faults. Unless a fault is unacceptable, it can be overlooked.
A few years ago, when my hair was still dark brown, our community theater company cast me in the role of Dracula. To portray him successfully, I could not see Dracula as mad or evil, but instead recognize that he saw himself as a superior being who regarded lessor humans as cattle.