I go out between one and three times a week, sometimes with the guy I'm seeing, sometimes not. Either way I won't dance with random people- they're liable to take it the wrong way, especially guys. I also wouldn't dance with an ex. Friends I generally dance quite closely with, but, well, my boyfriend is much worse. Luckily I'm not bothered about him grinding on his best friends!
I'll chat to people but I won't flirt with them, and if it becomes apparent that they're trying to chat me up I'll bugger off.
Not actually that different from when I'm single.
It's okay to say 'no' to people, so long as you do it politely.
Maybe you could talk to her about it- but stress that you're the one at fault (being insecure) rather than there being a lack of trust. Could also mention something about how she's so beautiful you're worried about all the attention she'll get.