One t re-framed that for me when I was talking about attachment... she asked why it would be weird to miss someone you saw regularly for a length of time. I have clients I've worked with in the past that I still think about. There's a level of investment needed to be able to effectively do the work. It doesn't have to be much outside of the session, but generally gears are still turning at least for a few minutes between sessions...
I think t's enjoy working with some clients for various reasons, but they should be able to keep it professional. It should never cross to pressuring a client to remain as one. Nor should the therapist be using a client to meet needs beyond the basic business relationship the t was hired for (getting paid for their work).
What gives you the impression that t is attached to you? (no judgement in that, just asking).