Help me understand the fairer sex?

There's a lady at work who's quite sombre and straight, by that I mean she doesn't take fools gladly and those who work for her either have a good relationship and get on well as they deliver or feel put upon and dislike her immensely. She rarely smiles or lets out her emotions, but as her former boss I know she has a hard exterior yet a soft inner side. I liked her from when we first met, and she delivered - I encouraged her to smile more, relax and be more warming to others, gave her good markings on her appraisals and helped her get good pay rises and rewards - eventually leading to her promotion. We had one night of semi-passion together, by that I mean I ****** up and bought no condoms earlier in the day even though I kinda knew the chance was there, and couldnt get any when realisation actually dawned later that she was indeed willing - so we did everything but - however it turned out to be a one night only thing instead of a more meaningful affair. Now, I cant get her out of my head, and it's a year on. At times she's talkative, warm and we can spend 2 hours on the phone just chatting - other times she is dismissive, hardly gives me any eye contact or go's off her instant messenger at work for days on end. At times she will divulge the most personal of things to me, looking and asking for advice like a soulmate rather than just a colleague or peer - at other times I'm like something she stepped in...... any ideas what the hell she thinks of me?