The Dark Side is its own mental disorder.... I’d call him a guilty spark if anything; when his mother died and his following actions.... This action was far more definite than his "attachment" to Padme, which is quite understandable when his history is looked at objectively, i.e., no "father" due to his mother being the Virgin Mary, leaving his mother at an early age and not seeing her until her death; unable to save her from death..., Padme being his new mummy....
He sounds like a normal human to me (until his eyes went "red" that is and he started cutting down children).