I doubt it's intentional manipulation. Some people just have chemistry--sometimes romantic/sexual, sometimes just more that you "click" with someone in more of a platonic way. And it can be hard to turn that off. That could be the case with your T, that you guys just "click." So you may not be imagining things. And if it feels like flirtation, I sometimes suddenly realize that I'm subconsciously flirting with someone (like former coworkers, etc.), and it's not like I was overtly like, "OK, I'm going to flirt with my coworker now." Ideally, your T is continually in touch with and checking in on his feelings regarding his clients. But sometimes things like a certain glance or body language just slip out. Your other therapist acting like you're insane for thinking that...that's likely her just trying to protect both you and your other T in a way. Like trying to keep you from thinking there could be something there, because you'd just get hurt. And trying to not suggest that your T could be acting unethically in any way. But I'm sure it's frustrating for her to basically say it's all in your head...

So maybe there is some sort of attraction or chemistry there. It might not all be in your head. But assuming your therapist is ethical, as you say, then nothing will ever come of it. Which is how it should be. Keep talking about your feelings with him--it can help to get those out. But know that if you, say, directly ask if he's attracted to your or has romantic feelings for you, that ethically, no matter what he actually feels, he has to say that he sees you as a client and nothing more. I mean, certainly, he can say he cares about you in a platonic way. But if he were to say, for example, that he's attracted to you, then he's crossing a line that can't be uncrossed. And that would be unethical. Because then his thoughts and feelings would be getting in the way of the therapeutic relationship. Plus he'd be leading you on...

I say all this as someone who has had, at times, erotic transference for my marriage counselor. It has since shifted into more paternal transference, if anything. But there were definitely some moments, back when I was really feeling the erotic thing, that it felt like there was maybe something there. So I get it. But I realize now that it's probably more just that he and I "get" each other, like we're fairly similar in how our minds work. And because he's of the gender that I'm attracted to, my mind automatically jumped to "It's attraction." When it's really more a case of being on the same wavelength than of a physical/romantic thing. In the same way that I have some platonic friends that I just "click" with.

I hope this answer made some sort of sense and was helpful in some way...