The problem is the weekend with the men. No one that I know would be ok with this. Well maybe the couple that play around might, but they always do things together, so they might not be ok going solo.
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It is respecting the one you are with. Op's GF has already gone other places with out him and he was fine with it. He is just not ok with her spending a weekend with two guys she nor he knows.
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Wookin, unless you are in a traditional relationship where it's agreed that the man is the boss, DO NOT have the right to forbid a partner from doing anything. She is your partner, not your child.
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You have the right to express an opinion. You have the right to walk away if you don't agree with what she's doing. But you do not have the right to make decisions on her freedom or otherwise control her.
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