<human>: My boyfriend and I have been dating for little over a year. Before we were official I knew he had a FwB but he stopped seeing her before he asked me out officially. 

I have a really high sex drive (or at least I think so... I never say no and normally initiate sex) so when he asked I was a little offended. He said he misses the spark or tension that is in the air when you sleep with someone new for the first time. I told him no and that I wouldn't mind a three some or a couple swap (I have been researching that for a while and on okcupid as well if you know other places to look I would be grateful) but no just random hook ups. I wouldn't take advantage of it anyways and would just feel sad. 

Well the next day we are driving to the city with some friends and he brings up the topic why would it be a bad thing to sleep with other people and started the conversation with everyone and I told him because it makes the other person feel bad and well cheated on. 

He just doesn't seem to be getting how hurt I would be thinking I am not doing enough. He swears up and down he still loves our sex life he just is missing that spark of sex with someone new.  My one close friend said something along the lines of eventually he might just go for it without permission and that makes me feel sick to the stomach. 

My question really just is how do I make him understand how bad the idea of it makes me feel? He says he wouldn't care if I slept with another guy but I am not like that.  Also should I worry about him just going for it without the permission? I have a serious zero cheating policy in the past but this is my longest relationship I have ever been in. Someone already mentioned to me maybe he already has done it and was just checking for forgiveness instead of permission. 

Thank you for reading.

Could you distill the essence of the text into 1-3 sentences?
<bot>: boyfriend asked for an open relationship and I just don't know how to make him see how bad the idea of him being with someone else makes me feel.