This has been my experience of desire and longing in therapy and with my therapist, in that it's the absence of certain kinds of healthy relationships that make the transference bloom for me. It's like it was a clue for what I was missing in my marriage and/or other relationships.

For me, it was similar to when I've realized that certain relationships weren't good for me. What that unhealthy relationship brought me-- the most recent one, for example, was easy companionship and deep, intimate conversations. These needs are hardly unhealthy but for many other reasons, this relationship was, and I was willing to suffer for them.

I don't presume that transference is the same for everyone and it's kind of a stereotype to pitch therapy as useful only for those who don't get what they need from healthy relationships. It is perfectly possible to have a healthy and happy marriage and still experience transference or struggle with attachment. However, I do think it's worth exploring whether your marriage and other relationships are working for you in the overall picture of the changes you are making in therapy.