Iago, maybe I'm wrong - don't take my advice for it, but you need to steel yourself now. Ask her one question. "Do you believe that without this freedom you want, you can not be happy in our relationship"? If her answer is "yes", there may be no solution but separation. You want her to be happy, but you won't be happy if she's with other men. Something tells me you're not the type to enjoy the idea of sleeping with other women. It was wrong of her, in my opinion, to wait until this late stage before bringing this up with you. If she knows you're not happy with it, and cares more about her own happiness than yours, she's already made her choice.