I have felt love for my T and felt loved in therapy. Not erotic transference or a longing for a "real" relationship in any sustained way. I'd be hard pressed to say that the experience of love is ever harmful. Sometimes it's the impact of "love" that is harmful, such as because I loved him I ______ (insert inappropriate behavior here). The feeling is one thing, then acting on that feeling is another. I'm talking only about feelings here in therapy, don't know if this is what you meant.