What kind of joke is this?
Native speaker’s answer
Rebecca
He is joking here that the person would not be perfect for him if they were actually "perfect", but if they were "co-dependent" and "self-destructive" then they would be the perfect person for him. He says this as a joke because he thinks that he is "co-dependent" and "self-destructive", so if someone else were like that too, then they would be a perfect match.