It's something I realized because I started to notice that whenever I talked about something "big" in my relationship with him and got to the underlying issues along with the sense of relief was also a shift in my feelings towards a more paternal mode. But my T and I have also discussed that because of the sexual abuse my expectations of relationship became warped so that I have an expectation of sex needing to be included in order to get what I need from a man. He has also likened my feelings for him to a little girls' saying "I love you Daddy, and I'm going to marry you when I grow up."
I also totally agree with what you said about endorphins and our desire/attraction/arousal mechanisms. I think our sexuality tends to be very complex and is highly impacted my our early relationships so when we are dealing with such strong desires and emotions like the one's invoked by our T's and needs that were never fulfilled, it makes sense that it "bleeds" over into our sexual desires. From reading I've done, our desire to merge in a romantic/sexual relationship with no boundaries between us and our lover is very akin to the merger we once knew with our mother when all our needs were met and there was no boundary because we didn't know an "I" existed at the time. So it all fits.
Sometimes I spend a lot of time trying to figure out the nature of the my feelings and other times I realize its not really that important. The boundaries of the relationship are really clear and carefully maintained, especially by my T (which is why I trust him) and he's phemonally important to me for a lot of good reasons. I try to leave it at that.
But my T keeps telling me that coming and talking about all my feelings especially in relation to him is how the work is getting done. I can never figure out if his wanting to hear all this is a sign of incredible compassion or complete insanity. 
But I'm grateful for it either way. It is easier when the erotic pull isn't very strong, it can get pretty distracting. I hate sessions where I realize that I'm just sitting and looking at my T instead of listening to what he's saying. Haven't gotten snagged so far that i know of which is good because I would die of embarrassment.
Although the man never looks flustered so I'd probably survive it. He's stayed very calm when I've talked to him about how obsessive the relationship feels.AG