<human>: Could you distill the essence of the text into 1-3 sentences?

I love my girlfriend. She is fucking gorgeous, funny, smart - she's the real deal. I'm going to marry her one day. I've never met someone so compatible with me. 

However, there's something that's been nagging at me for quite some time. We have fairly vanilla sex. It's great - but it's pretty standard. I want to explore sexually and I want to involve other people. The idea of going to something like a sex party, or having a threesome turns me on quite a bit. Heck, just WATCHING my girlfriend have sex with a girl is a huge fantasy. 

Here's a short list:
- I want to explore threesomes. Even just doing it once is fine. 
- I want have someone watch me fuck my girlfriend (guy or girl)
- I want to go to crazy sex parties. Maybe a swinger party - or some sort of orgy. 

I want to do all these things WITH her. Her being part of it is an integral part of my fantasies. I want to explore our sexuality together. I want us to tag-team and seduce a girl together. God, that seems like it would be so fun. 

But the problem is, how do I bring this stuff up? She's revealed some of her fantasies to me and based on that, I think she would be open to trying this stuff. But I'm afraid that if she's not she'll think negatively of me for wanting to do these things. 

Up to this point it's been easier to just push aside my fantasies because the fear of her not being accepting scares me too much. Which is honestly just my hang-up because I don't think she would react negatively. 

Anyway, how should I bring this up? Are there books or anything that walk you through this sort of thing?
<bot>: I want to explore sexually with my girlfriend (threesomes, sex parties) but I'm not sure how to bring it up to her.