First, she is dating a son of God. Thinking and calling him a lose only makes it harder for you to have any influence. Second, you really don't want to make this about him. She feels loved. She sounds like she may be being isolated, emotionally abused, and gaslighted. What she needs from family isn't criticism, but some knowledge that she is competent, that whatever mistakes she makes, she can fix them (it is entirely possible that she has been done things with him that makes her feel unworthy and that she needs to be with him, though maybe not), that she deserves to be treated well (and what that looks like). Find ways to lighten her life. To help her see and live goodness and light.