I picked the first option: it was the situation.
I had no experience of positive attachment; she was consistent, calm and dependable. If I remember correctly my attachment to her took quite a long time (at least several years).

That was with ex long term t. I have seen several other Ts with whom I haven't had the same attachment. Ones prior to long term t I guess I didn't attach because I was frozen and immovable; a couple of other Ts I didn't attach to because they were idiots.
I am not attached to current T - I have only been seeing her a short time and, thanks to long term t, I don't have the inner need to attach in that manner anymore.

Edited to say: My feelings for t have been of the attachment / longing for a motherly figure kind.