I'm glad you brought this to the forum, the situation is tricky.
She started flirting with you after her boyfriend cheated, this is most likely her being hurt and (unconsciously) looking for a rebound. From what you said, she is probably into you, but unfortunately, not into you as much as you think. You spending so much time with her (during a regular day and business trips) and enjoying flirting with her WHILE NOT HAVING ANY PLATES is clouding your judgement. She is all you see. You are too close to the situation to see it clearly my friend.
The DJs saying you should go for it may be forgetting that you are not her manager, you are the BUSINESS OWNER. The ramifications if this goes sour will tarnish your reputation in YOUR OWN BUSINESS perhaps beyond repair (at least a manager can switch employers, you cannot). Women talk, employees talk, young women especially will talk with anyone with half an ear (you are not the only one she speaks with about her ex's infidelity). Others around the office know too. If you start ****ing her, others will know. No one forgets. I join companies and hear about things my boss did 5 years ago from fellow employees without even asking. You know she is attracted to you and
@Alvafe (rightfully) mentioned that it sounds like maybe hoping there is a good reason for banging her. While this may be a really fun exciting experience and certainly a infamous tale for the history book of your life, you will almost certainly regret it.
As far as her behavior the other day. It is clear that she is still hung up on her ex. The moment she has to go meet up with his sister all the feelings of him are rushing back to her mind, you are forgotten until she is ready again for you. The feelings she has for you are shallow at the moment. I'm curious what you think is the real purpose of her meeting with her ex's sister. It's most certainly an expedition for some sort of repair of the relationship (on her part or the boyfriend's part). At this meeting she will find out from his sister how her ex is doing, they were so good together, blah blah. A good portion of them "chatting up and bonding together" will be centered on her past relationship. Her ex's sister will of course not condone her brother's infidelity but at the end of the day, be a diplomatic advocate for him in one way or another. Bottom line about her behavior is that she was so focused on her ex and meeting up with his sister again that she could not show you all the regular trappings of a good office flirt because there was none to give at that moment. Her feelings allowed her to detach from you easily. Depending on how that meeting goes with her ex's sister she will go back to her normal flirtatious self (if there is no sign of them getting back together) or she will drop the flirt act and leave you even more confused and feeling stupid/questioning yourself about if it's something you did.
I commend you that even though you are in a state of confusion regarding her behavior, you maintained composure. My recommendation to you would be to remain stoic and don't bang her if the opportunity arises.
