Life gets crazy

I find myself in an interesting situation. I've started seeing a fantastic girl, i'll call her butterfly. She's smart, gorgeous, sexy, witty, totally into me...and she's married.
I knew before we met that she was in an open relationship. She had explained it in her okCupid profile, so I entered this eyes-open. My problem now is I really like this girl. We could have a great time together, only if her husband gives her the ok...

I have no problems with open relationships at all. In fact, i've always thought i'd eventually meet a fantastic woman i'd settle down with and we'd have some form of open relationship to keep things interesting. I just didn't think i'd ever be on the outside, trying to get in. I also would have never guessed how much I could like this girl.

It was amazing chemistry from the second she walked into the bar when my first though was "oh. my. god. she is fucking gorgeous!". 5'11" with unbelievable legs, wearing a slinky sundress, stilettos and a flower in her hair; she was stunning, and just my type. The conversation was easy and engaging. We drank and flirted shamelessly. I'm sure everyone in the bar could see the sparks. I suggested a dance club nearby as I wanted an excuse have her body against mine. She clearly wanted it as well and practically dragged me out of the bar. At the club, we danced pressed together, slow and sexy. Talking and flirting and touching, it was amazingly sensual. The club closed and as we walked, it was obvious both of us wanted to get the other naked and do amazing things together. It would have been amazing. Would have been, because butterfly's arrangement with her husband requires prior approval before either of them sleeps with someone new. We respected her rules, but putting her in the car with just a kiss was an amazing test of will power (for both of us).

So, now i'm in this weird limbo. I want so badly to just dive in with this girl and enjoy the ride, but I can't. I have to take things slowly, get to know this guy and try to convince him i'm worthy of his wife's admiration (and her sex). It's an interesting situation, having to court two people to date one of them. I'm used to having only to worry about my feelings and hers. I'm pretty good at that actually. I am totally at a loss when it comes to persuading another guy to let me sleep with his wife. I'm fully aware of how absurd that statement is.

Honestly, if it were any other girl, it would not be worth the hassle. She might be worth it. It's freaking me out.