I think there is more than one answer. There are different ways a healthy relationship could look.

I've had two therapists. With my first one, I had a "neutral" relationship. Not unhealthy, but not shiningly healthy either, just neutral. Kind of blah. No attachment or dependency there. No real connection.

With my current therapist, I think we have a healthy relationship. There are genuine moments of emotional intimacy between us, and neither of us is freaked out by it, neither of us retreats or pushes the other person away, and neither of us encroaches on the other's boundaries. We connect fairly easily at our sessions and both of us can be fairly direct in communication with the other. I'm secure in the relationship. I don't worry T is going to ditch me or that T hates me. I don't obsess about my T, but I care very deeply about him. I feel a lot of empathy towards him. When he sustained a dangerous injury to his face and told me the story of how it happened, I shook a bit and couldn't help crying. Some might think that is a tad too connected , but T thanked me very sincerely for my empathy. I don't get angsty when he is away on vacation or get angry at him for going away. I miss him when he is gone and am very happy to see him upon return. I don't call him or email him in between sessions or stew about whether I should or not. I don't resent his other clients and wish I were the only one. I don't get jealous of his wife or other family members and wish he would take me home. I feel strongly and securely attached to him. This does not make me feel dependent on him. I trust him to always have my best interests at heart. Our bond helps us do trauma work and go deep. We hug sometimes at the end of our sessions, but not all the time. It can be great when we hug, but it is fine if we don't--I don't feel like the world will end and I know it doesn't mean we are mad at each other or that there is something wrong in our relationship. There is a lot of give and take in our conversation--a lot of reciprocity. Also, T seems to "get" me and I think I "get" him too. It is wonderful to be understood at a deep level and have someone genuinely curious about one's life and solicitous about one's welfare. Once T and I were having an emotionally intimate conversation--back and forth, not just me telling him--and he paused a moment and then gestured at both of us and said, "this is Health." So I hold that in my mind when someone asks what a healthy relationship is. I hold that "Health" up as a model for how I want other relationships in my life to be.

It's not a perfect relationship, but I think it is a Healthy one. It didn't happen overnight, but has developed over time. (In our first months, the attachment was less secure.)