Your comment is short sighted and hurtful. Someone who has an avoidant attachment type does so for a reason. Usually a reason that happened to them when they were young, a reason that wasn’t their own. They have probably struggled with this (non) understanding for a very long and bewildering time, until they find the answer. That answer can be scary and huge and littered with unfair and obtuse comments such as ‘narcissistic’ and ‘selfish.’
Would you call someone with depression or anxiety selfish? No. You would show compassion and understanding. Try the same with attachment types. It takes a lot of work and insight to understand how someone’s attachment type affects them and how best to address it and work with it. A partner who has made a success of a relationship with an avoidant or insecure partner deserves commendation, not to be jeered at. In my eyes, the only sad and ignorant people here are the ones like you – the real narcissists and people with a chip on their shoulder ;)