I wonder if reframing it might be helpful... as in instead of using this need to see and know who her boyfriend is in an effort to get closer to her, what about getting closer to her by respecting her boundary? It is a gift to her to respect her boundary. It has the potential to bring you closer together rather than further apart. It is an act of love for her to know her boundary and honor it. It has the potential to make you more trustworthy in her eyes.
What is it like if you imagine yourself fighting against that urge to unmask him and saying to T "I know you didn't want to show me so I stopped searching for him out of respect for you." How would it feel to be t and hear that? How would she react? How would you feel about her reaction? How would that affect your relationship? How would it strengthen it?
I think there is unexplored potential for change there. because respecting her boundary has the potential to strengthen your relationship in trust and commitment.
To be respected is such a gift.