haha ok, the interesting stuff. what's great about having a girl there is that now it comes down to your freestyle and expression. (and because girls' bodies feel nice).
You're right turn the footwork down a lot, I still use my hips but yea everything gets slower and subtler. Your hands will mostly be on her hips but you can let them wander

If it's done with flow you can touch her anywhere. Pulling hair gently, spinning by the neck is a nice one, you can even hold her face close to yours like you're about to kiss her then spin her away, stuff like that. When the beat drops out and the song gets slow is when I'll slide up against her really sensually almost as if we're about to f**k then when the first bass hit comes back in I'll grab her hips and pound her once lol. You don't have to get that sexual it's just one of the things I might do and shows you can still follow the music but in a sexual way and directed to her. Variety is exciting here and don't be afraid to be dominant.
The way I see it, if you enter a club and you're grooving alone you're sort of 'performing' for a/the girl. Once she enters your space you dance together but now more like she is 'performing' for you. So I'll push her away and make her dance alone while I stand back almost still watching her. The great thing about Groove is that you can just be tapping your foot or rocking your head back forth really gently but still be completely feeling the music. And you 2 will have your own little bubble so even if you push her away, step back and bust some moves alone she will come back to you.
So then you pull her back in and pull her ass up against you. If you can match the movement of her hips that's cool. It will depend on how good of a dancer you both are. If a chick has shitty rhythm I won't move my hips much I'll more let her do her thing. I'll also get more physical quicker and try to leave sooner. If a girl is a good dancer, then I might focus on that and enjoy it a bit more. I actually like dancing with girls so they're more open to that vibe.
Also it's less about doing specific moves now and more about being spontaneous and feeling her energy. As you practice you will find little techniques that work for you in different situations/positions.
Hope that helps