ria75, I have never been too clear onn Bonding. Don't believe it was adequately explained on the series of if it was I missed it.
My belief (and it is only that, a belief) is that as T-Pol said, she and Trip Mated. I think that is different from simple Sex or a one night stand.
I believe that for a vulcan it is a comittment of some sort.
with Phlox it would have been Sex but could have been considered a mating by T-Pol hence a Bond. But as I remember the episode there was not indication that Phlox and T-Pol had Sex and that Plox answer to T-Pol was typical Phlox, a joke.
Frankly do not know so am in the dark and just groping around.