<human>: I have been with my amazing girlfriend for 9 years.  We have a great sex life, and lots of great friends together.  Though, not many activities in common together, other than some TV shows we like.  Other than that, things are very good.  We've lived together for 2.5 years, and I was hoping to be able to afford a nice engagement ring for her this year.  
Our engagement has not formally been established for a couple of reasons - primarily want of money and needing to get settled career-wise.  Over the past year, those things are starting to come within reach - I have a leadership position at a job I enjoy, and financial comfort is becoming established.    

At that job, there is a young lady who I think is very interested in me.  30ish, beautiful, very kind, and with some mutual interests.  No idea why she's single, other than the fact she is a doctor.  I can feel a very strong mutual attraction, and she's always asking me what I'm getting up to on the weekend, telling me about her plans, dropping hints that she is single.  If she mentions something social with a man, she'll tell me he's gay, or just a friend, etc.  I feel like she's leaving the door open for me to initiate something.  The tension is killing me, and I find myself occasionally thinking about her when I'm not at work.  Here's the part where I feel guilty - I've never given her any idea that I have a girlfriend. 

I appreciate any thoughts on how to best deal with this.   

Thanks for reading :)

Can you give me the gist of the text in a nutshell?
<bot>: Have a great girlfriend who I love; also feel mutual attraction to someone else at work; wracked with guilt and temptation.