Well.. i've been in your exact situation before.. and it didn't end pretty..
At least the journey was memorable, but the final price I had to pay was not worth it at all..
Two of my closes friends were dating. (Let's call them Bob & Grace for the purpose of privacy). So, we knew eachother for 2 years! They were dating for all 2 years, on and off, he would cheat on her, but they would get back together, he would hit her, but they would get back together, he would neglect her, but they would once again end up back together..
So, during the course of these two years, I had grown closer to Grace as a result of feeling sorry for the way she was being treated. In fact, I started to build up disfavor for Bob. So, they were actually on break, (not seeing/talking to eachother). During that time, he slept with two other girls, and she found out later from her friends.
Long story short (if that's still possible), her lack of a significant other really got to her, and since I was the only male figure in her life at that point (besides her father & brother), she started having feelings for me. And, like you have pointed out, Grace was also very attractive.
I was then faced with a dilema inside my mind, (Bob has been a good friend, and I have morals, i'm a loyal friend, and no matter what their current situation is, it feels wrong, so I would never do anything with Grace). Well, obviously, actions speak louder than words.
One afternoon, me and Grace were home alone.. and since you see where this is getting... she initiated a make-out session.. (now, at that moment, as much as I tried to think about Bob, and how I shouldn't be doing this, my feelings of pitty & compassion for Grace got in the way, coupled with strong sexual tension & attraction.. it was a disaster waiting to happen). Well, things got turned up a notch, and that lasted for about 2 weeks, until Bob found out!
Well, i'm quite the diplomat, so it didn't result into anything physical, but he basically gave me an ultimatum, (Him, or Her?).. well.. at that moment, the answer was easy.. (Her).. so goodbye Bob, my close male friend for the past two years.. in a matter of one phone call. After I hung up the phone.. I just realized what was going on.. I was stuck with Grace.. and while there was strong sexual chemistry, the girl was a wreck! I mean, it was great being her friend, great being a little bit more.. but going into a relationship with her was like doing an internship for a Psychoanalyst..
So, I believe a week of endulgence when by until me and Grace started feeling akward. So, we stopped meeting up, then we stopped talking, and then I found out that she was dating Bob again.. There went 2 of my best friends, out the window, for what? (a 3-week spree?).. I realized that it was totally not worth it..
Especially since after that, they ended up breaking things off for good. Bob was dating random women for short-term periods, while Grace ended up getting engaged to an Electrician ($78,000 a year, yikes!)..
So, if you want to go to a movie together, go ahead, and it's good you want to help her... But don't fall into the trap of developing feelings for her out of pity or feeling sorry for her... It's not worth it, and it's VERY short term, with VERY long-term consequenses..
If you can't stop the Wind, then you can't stop the Storm.