I don't believe we give others a reason to, we may, however, provide support in light of their recognition that they need to change and make the necessary steps to achieve it. But, one person's support is another's enablement.
Yes, I've was in a (vanilla) relationship for four years with someone I now realise was a classic sociopath - although it wasn't until I started reading recent posts on here that I realised she fitted the profile to a T, and just why the relationship was so painful and destructive. Thanks CM - I've learned something, and at least been able to put a label on a problem now and file away some of my ongoing guilt at the failure of the relationship.
I'm married to a paranoid antisocial. Its caused untold amounts of problems and stress. The person who fits that bill does not see themself as having the problem. They are convinced its everyone else. This is a problem that is so far ingrained in the individual, that there's really no way of changing this behavior.
And mental illness and personality disorder are considered two different things. Which in my mind makes it that much harder to get help for the person and family. God bless and be with those of us who go thru life with family members who don't function the way we wish they would. That is not a heartless thought. I feel for humanity. Very much so.