<human>: Can you condense the text into three sentences or less?

Hi, I'm a female (23) in a monogamous relationship. My boyfriend (27) has had three long term relationships including me, from his teenage years til now, and hasn't explored that much.

 There was not a very long space between me and his last girlfriend. And he didn't really get a chance to be single. We just got sucked into it without thinking, 2 years later and both of us feel like we'll probably be together a long time. 

It came up in conversation today that maybe he could have sex with other girls, first joking, but then became quite serious, as I actually have thought about this before. And wondered if it would be healthy for us. We are very open with each other, and it would purely be for the excitement of sleeping with a few people.

I have had more partners than him, though none anywhere near the level of caring, and the sex that I have with him. I don't feel like I've missed out, but I do feel for him and he does feel like he has missed out. But would never expect or even ask this from me, I'm the one who's pushing the subject. He is interested, but would not risk our relationship if i did not want him to do this. 

 I want to let him sleep with other people, but only no strings attached. He is going away for two months soon, and I think this would be a good time to explore that. I'm not jealous sexually, but I don't want him getting emotionally intimate with someone else.
 I wonder what rules should be in place to keep these interactions appropriate. I don't want him to be spending too much time and effort on other girls, as I feel that would be unfair on me as I'm not planning to date anyone else.

 Has anyone else been in this situation? Or anything like it? I would love to hear anyone's opinions, ideas or experiences involving this subject?
<bot>: I want to let boyfriend sleep with someone else to allow him to explore, wondering what is the best way to go about it.