Girlfriend goes on holiday with new male friend

Hi, I have been in a relationship with a girl for almost 4 years. Our relationships has had it's problems, ups and downs, but until last Monday, as far as I knew we were still in a relationship. I found out last Sunday that back in February 2012, my girlfriend went on a cruise with a new 'male friend'. She told me she was going with a girlfriend and I believed her. She went with this 'male friend' for a weeks cruise, sharing the same cabin, albeit single beds but the same cabin and bathroom. When I found out about this I terminated the relationship as it 'sickened me'. She says that she has done 'nothing wrong' as he was just a 'platonic friend'. I cannot agree with this and have felt physically sick since finding out. I feel that she was very wrong, firstly for arranging the holiday with a 'new male friend' (I had never heard of him and we had been together for over 3yrs), she totally disrespeced me in going and planning this holiday, lied to me about going with her girlfriend, she never even told her girlfriend she was using her name in vain. She is still protesting that she has done nothing wrong ? Please express your views on this, whether you be a female or a male, was she wrong ? What would you do if your partner did this to you ?

Sorry to say this, but she lied by saying she was going away with a 'girlfriend'. Even if it turns out to be 'just a platonic friendship', she must have known you would not have

Hi, sounds like as well as the ups and downs of the relationship there were other communication problems within this relationship. I would never condone a partner doing this to the other. Have you asked for an explanation as to why she thinks this is doing nothing wrong? Is there any other reason why she would do this to you without asking your permission or finding out how you would feel about it? Perhaps there is an explanation you could explore if you felt it was worth finding out about...if not then perhaps your wanting this relationship over, good luck.