Thank you for your question.
Without talking to her, it would be impossible to say for sure. Tell a little bit more about her:
1. Is she married or does she have a boyfriend (or girlfriend) outside the office?
2. Do you go on dates outside of work?
3. Are you married or involved?
WE both are married and she has worked for me 6 years.
If you have not been dating, then in my opinion this is not leading to sack time, unless something changes.
Right now you are describing a classic flirting game, that for her, would be safe. You would have to become more aggressive, not physically, but in terms of the NEXT move.
it appears this game is stuck at the next move level.
The next move being, an actual date, or something you arrange in the office that resembles a date.
I also believe you are at risk for a charge of sexual harassment, even though she appears to at times encourage the behavior. What would happen if her husband were to find out? How will she respond to that? in many cases, women in her position would respond by going on the defensive and making a charge of sexual harassment.
I do not know how she feels about her husband, but this has the appearance of a flirtatious game that is safe for her. She can flirt with you during the day, and go home excited, and take care of her husband.
The only way you will know for sure is to bring it to the next level.