I am a straight female and he's a straight male. We started out traditionally monogamous, but it's not like that anymore. It did take me some time to warm up to the idea and feel secure in it. But I actually almost feel more secure now than when he was obliged to sexually faithful to me.

So yes, he is free to sleep with whomever he wishes to sleep with, so it is sexually open on his side. I wasn't always comfortable with it, but he is extremely honest and it's abundantly clear to me that for him it's purely lust and changes nothing about his feelings for me, and it's also just a given that no matter what, the sex is always the best with me. So what I'm saying is I don't have insecurity about his love & loyalty for me, or his sexual satisfaction with me, and our sex life is amazing. It's not so much like he has other girls to hit up on a regular basis, but more that if there's a party and i'm not around, he has the freedom to go crazy and hook up with someone random. There's not really hard rules, but I trust his discretion, communication, and maturity.

In theory I could sleep with other men, but in practice no. It's not that he prohibits it, but just that we mutually agree it doesn't really work. I'm very much a woman's woman I guess you could say, and I don't enjoy meaningless sex. So if I had sex with another guy, I would need to have genuine attraction, which is so rare for me to begin with, and would probably signify feelings on my side for the guy. But we are completely emotionally exclusive, so it doesn't work. I don't really want to either. I just don't, and besides, let's just say he keeps this lady extremely happy.

It works for some reason because of our sexual and relational dynamic, and the fact that I trust him completely. I wouldn't just let any guy I date do this, it might be a dealbreaker... Well anyway I wonder if this is common or not, and I don't even know the word for it. We're emotionally exclusive for each other, but one-sidedly sexually open..?