Well, I’m no expert, but I’ll give it a shot. My advice would be essentially similar to Cletus’s, but coming at it from the opposite side. I would suggest you try to embrace it, rather than reject it.
If you can learn to accept it, you will then be in a position where the issue leaves, on its own. This is hard to do, but it can be done. You like this woman. So, accept that this is who she is, and like her even more for being free to have fun with people. She enjoys connecting with people, and having fun, and she’s chosen you as one of those special people with whom she wishes to have fun.
Coincidentally, Rhino’sHoney happens to be one of the women of whom I could easily become jealous, and probably would have, in the past. I have flirted with her, perhaps outrageously. She has flirted with me. Instead of being jealous that she also flirts with other men, I accept her for who she is. I see her as one of life’s gifts, spreading happiness wherever she goes, through her zest for life. I suspect the lady you refer to is another such gift.
Then, you need to accept your reaction. This may be even harder, if you’re at all like me. But, try to give yourself the same understanding you would like from others, or would offer others. We’re all flawed. If this is your worst flaw, you’re practically a saint. Jealousy is a very normal, natural reaction.
It can be ugly; it can even be hateful. But, it is so, so human. If you can accept this, embrace it as part of who you are, and recognize that it doesn’t make you a bad person, or even an unusual one, you will find that it loses its power over you. Then, you’ll be ready to let it go.
This is something that you’ll need to do when you are not around this woman. And, it may take some time. Give yourself that time. Work on it. I know this is a very difficult task, believe me. But, if I can do it, you can. I’m about as unforgiving of myself as it’s possible to be, as a rule.
And, realize that much of it comes from your current state of mind. If you were more content, it would not have nearly the same effect that it does, currently. You may not be able to change your contentment level, at the moment, but recognizing it as a mitigating factor will help. Once you determine how much of your reaction stems from this source, you’ll be able to filter it out, and be able to assess the situation more calmly.
I hope this helps.
Rhino’sHoney, the wisdom, as always, flows from you as honey from the comb. 
