AS partner cheating

Hi, I'm new to this but my partner is recently self-diagnosed AS. He is very intelligent and high-functioning. I just found out that he's being cheating on me in a non-sexual relationship for 3 years with a much, much younger woman  (And, please, before anyone asks, yes, you can cheat without sex or even romance.) Having given this a LOT of thought I think this is more to do with narcissistic personality traits than AS. He's done online tests for various personality disorders and this one fits best to his characteristics, although I appreciate it's all very fluid. Any (helpful) comments or advice gratefully received. 

Parents
  • hmm rather odd, i mean most people with ASD struggle to find any friends or relationship anyway and remain forever alone.... rather rare for one to not only have a relation but also be cheating on that relation and having another. could be that his self diagnosis is wrong or not thought out well enough. what makes him think he has ASD if hes such a stud? lol

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  • hmm rather odd, i mean most people with ASD struggle to find any friends or relationship anyway and remain forever alone.... rather rare for one to not only have a relation but also be cheating on that relation and having another. could be that his self diagnosis is wrong or not thought out well enough. what makes him think he has ASD if hes such a stud? lol

Children