Here is my advice
Firstly you need to ask yourself some questions and to seriosly think about them , and belive me whatever I or Valence say , you are deciding so you must realy think this through
1.Is she the person you will hava most fun (as a GF) , or u can fun someone with who you can have more fun , and to be better looking
2.Do you want to fuck other people , i mean are you inloved in her , or you just like her same as your mother,friend or something you are very found of , I mean you said I love her but I don't want to be tied down , you also love your mother,friend your dog but you don't make a big fuss of it.
3.What will be better for you to try it once again with her or to have a open ralationship , think about it ,in which situation would you feel better , what situation will save you from that pain of being hurt.
There is not a good advice on this this is realy fucked up situation , so think realy good about it , you either try it with her or you don't .
And at the end you can allways try swinging thing together
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LOVE FROM SERBIA