Generally, convincing a partner to open a relationship is a bad idea. It’s better to frame it as something you’d like to try, and let them gradually warm to the idea through conversation.

But since he’s bringing it up, you can modify that. Be honest. Tell him that it’s a turn on. Discuss the boundaries, expectations and benefits. Let it build to a mutual desire, and it’ll happen naturally.

It’s usually a good idea to be very picky about who is and isn’t an acceptable play partner. Strangers vs friends are a totally different vibe. Men vs women. Emotional bonding okay or not. All the little things that can make the experience go good or bad.

Back in the era of my non monogamous life, if I was sharing with other men, it had to be a situation of mutual respect. No exceptions, no mistakes on that allowed or I was out and that meant out if the boundary wasn’t enforced by my partner as well. So it was almost always going to happen with friends, or in established groups for the purpose.

With women, I still insisted on that respect, it was just less likely to go wrong since even unfamiliar women willing to play were also usually all about agreements being done before play. Only ever had to call that rule into things once. Then again, even with men because it was always a mutually agreed process, it never had to go beyond a “hey man, remember we’re all here to have fun, it isn’t a competition” and it would be fine, no need to end the play.

Really, most guys that are bringing it up, all you gotta do is be patient and be willing to insist everything is hashed out before there’s other dick in you. Which is just as true if you’re all guys, as far as I ever saw, and it holds true if there’s no second dick involved at all.

I’ve been the second guy as well. So I’d say make sure that whoever you might pick is aware of your boundaries and asks questions that show they understand what is involved, rather than them chasing tail and not caring about anything else. It’s a hell of a lot nicer if you’re the outsider if your new partners are clear about big issues. Like, if the couple want a bit of role play where you’re playing bull, you need to know that. And the reverse is even more important; if there’s something like they don’t want you complimenting or encouraging either of them, you want to know that. It can be awkward as hell to express admiration of someone’s cunnilingus skills and they realize that they don’t want your input like that.

Remember, all the work it takes/took you and your guy to become happy partners has to be done for the third person, and it has to be right for both of you and for him/her. It’s not just you having sex with the third party, even if your bf isn’t in the room. There’s still three interactions in play. If you’re all in the room, every little dynamic might matter.

Also, since your question came with a pic, I don’t think you’ll have trouble finding someone, so you can afford to be picky.