need advice quick!

Ok so I am somewhat new to this. Been looking at everything. Anyways the situation is this girl that works at my gym sought me out. everything went good for awhile i knew she had a boyfriend. been going for about 3 weeks got the Last Minute Resistance and found out she's been with him for 5 years tomorrow and he may propose so she backed off now. She is 21 in college and hot has lots of hot friends. how can i turn this around and make her a friend to open new alleys rather than lose this apportunity?! I think it could be really good but how do you do it?
Any help is great! she's awesome and free spirited and may still be there but has backed away a little now. just want some advice.

addition. kissing and playing has been there all that and attraction is there just not getting any further.

Man you've just gotta be honest with her. Tell her that you think she's a great girl, that you know that sometimes when a man and a woman are attracted to each other they don't always think straight, and that you know that you and she have a little history that probably shouldn't have happened. But also tell her you respect her and her relationship (it sounds like you do) and that you have a ton of fun hanging out with her. Tell her you understand if she doesn't want to be a friend, but that that would be silly, because you guys have a great platonic relationship and you really enjoy her company. If you're cool and mature about it, she'll have a ton of respect for you.

The reason she backed off is because you were her "walk on the wild side". A young woman who is facing marriage may tempt herself with another guy to see how strongly she feels about her real relationship. She doesn't tell herself that's why she's doing it, but she does it anyway. She may always associate you with feelings of "cheating" or lying to her real BF... that is really going to depend on her... and there may be nothing you can do about it. But being straight with her about being friends is the best option - good luck!

thanks for the advice christian. She didn't get engaged and is pretty pissed about it but still said things need to stop. I was drunk and told her if he really wanted to make it happen he would no matter how old they are and she flipped. haven't heard from her since last night which has been odd.
we'll see each other at the gym when she works tomorrow. any advice for a little bit of clean up? lol
my plan is just go in act like nothing really happened. any other advice or link you may have would be very helpful.
she did get pissed when i told her i went to another girl's house from the gym to watch some football

Good idea. I've found that sometimes after doing something completely wrong, if I just ignore it and carry on - other people do the same. It may have to do with either having a strong frame and others buying into it, or even the fact that many times we over-read a situation and apply a larger value to it than it deserves.

thanks bill! I've been thinking i'm reading to much into it too. Just think i need to stay strong and show i'm not really affected or going to be the usuall puss she runs into.