I have to agree with Crisare on this one.
It's a very hard lesson to learn, but it's entirely possible to be completely head over heels in love with each other and *still* not be good partners for each other.
Love is necessary for a good partnership, but it is not always sufficient. This means that love is not always enough to make a partnership work, especially if the fundamental relationship goals are so different. One thing for sure, you will not find the solution you seek by setting controls and limits on her feelings about other people.
And one other thing. I notice that a lot of people tend to stay in relationships that are not necessarily good for them because people believe in a scarcity of love and that we must hold onto what we have because otherwise we may never find it again and be alone forever. With six billion people on this earth and an open heart, it's entirely possible and even pretty likely that you can find a relationship that's right for you and not one that is right except for some huge fundamental difference in goals.
The trouble is when we believe in the scarcity of love, it tends to be a self-fulfilling prophecy. It's like luck. Studies show that luck has more to do with how people perceive things rather than actual objective luck. So maybe take some time to consider what perceptions are keeping you in a relationship if there are fundamental things that aren't right for you.