How can i ask for a Threesome

So my boyfriend and I are committed to one another. We have sex a lot and I don’t want it to get boring. Some weeks I’ll give him head because he loves the way I suck his dick and I like to throw it back a little bit but we’ve been together for almost 2 years and he did mention that girl on girl is hot before and so recently I have been very horny and I heard my friends talking about how they’ve invited another person into their sex life for each other and it brought them closer together where as my other friend said she wasn’t really into it but did it for her man and they aren’t as close because she got jealous and all she thought about afterwards was how he felt about the other girl in bed, so I’m on the fence, like sure I don’t want to be jealous and I’m very confident but I haven’t ever done this with anyone so I wouldn’t know how I would react, but I do think it’d be hot to fuck my boyfriend with another girl, I’m not bisexual and I’m not attracted to girls but when I LOVE PLEASURING MY MAN. If he thinks it’s sexy or hot, it turns me on. I would love to try it with him.

However, it’s been a year since he mentioned girl on girl was hot so I’m kind of afraid that it might turn him off if I were to ask him for a threesome with another girl. Like I don’t want him thinking I’m not interested in our sex together (which he knows I loveeeee our sexual relationship) and I don’t want him to think I’m just wanting to be involved with a female, I just wouldn’t know how to bring it up in a conversation casually. 😂 help!