Since we humans are relational creatures the point of therapy is to help us have better relationships. We usually enter therapy having suffered from relationship wounds of various kinds. The therapeutic relationship is among other things designed to be a practice relationship for you. You can talk about things that make it difficult to be in relationship with other people, including (and maybe especially) your therapist. Then you take what you have learned and practiced, along with the healing you are experiencing into all your other relationships.
So I would take what your therapist said to you as a compliment, that you are progressing well in your work, that you are becoming the kind of healthy person he would want to be friends with, that other wonderful people would want to be friends with. In order to respect the therapeutic frame you and he will not become friends outside of therapy, However, you now have what it takes to cultivate amazing friendships with lots of other people you encounter moving forward.
Of course I’m just guessing here. The best way to know for sure is to ask him… and have a conversation about it. I bet he also enjoys working with you and wouldn’t mind you asking.