First of all, you’re not reading into this. She wants you to make a move. Second of all, the age gap isn’t a big deal here…. you’re both adults. However, the biggest problem is the fact that you’re her boss, and there’s a power gap. When you date an employee, you may be liable for all sorts of legal issues like favoring her over others, or if there’s a break up, punishing her by not giving her raises, projects, perks — because of the personal relationship. That said, lots of bosses and employees have happy relationships and even marriages, but you should be aware of your company’s legal policies regarding dating in the workplace.
My advice is that you take this relationship out of the shadow lands, where she winds up in your bed, sleeps naked in an adjoining hotel room with the door open, etc. and ask her out on a date, if that’s what you want to do. This will bring the issue of her boyfriend to the forefront, and you’ll get a lot more clarity than you are now. When you do ask her out (if you do), make sure you use the word “date” in the asking — especially since this relationship is so murky, it’s important to bring some light to what it is. Define it as dating by saying it’s dating.
Hope that helps! Let me know how things go.