I have been seeing someone for the past six months in a sexual relationship with someone who told me from the beginning that he is not monogamous. I chose to ignore this and proceed with the relationship anyway. We had some great, fun times and he is very loving when he's with me. But every so often reminders of his polyamory would come up and I would then attempt to "break up" with him. (Inevitably and eventually I came back.) This weekend I encountered evidence that he is and has been seeing someone else all along, and he's bringing her on a trip with him next month. I am hurt and consumed with jealousy and have now broken up with him again, hopefully for good. I just can't deal with the lifestyle, though I understand why he is in it... it's just not good for me. It's crushingly painful for me and yet I know it will be hard for me to forget him and move on - though I need to. This is where I'm at right now.