What would you do in this situation:

My current long term relationship is with a girl (29 yrs old) which is good looking, fun, and shares my interests. Everything's great. What annoys me big time is that she's a major attention whore.

See, she's grown up in an environment full of older males, and she hanged out with males from an early age. She's learnt very quick that the best way to get a male's attention is to tease him, and she does it like a professional - touching, eye contact, body language, she does them all. And she hasn't stopped at all now that she's in a relationship - she acts as if she was single in that point of view.

When I point that out (jokingly, of course - hell to me if I was ever to act clingy) she says that's just the way she naturally behaves and she doesn't do it on purpose. This, as crazy as it sounds, makes it sense when you look at the rest of her personality : she strives for approval from everybody and the quickest way to have a male give you some is to give him a boner. She has 20 or so "friend zoned" guys rotating around her and when I tell her that they would sleep with her in a glimpse she replies "no way! They're like brothers to me!" (I felt honestly bad for the poor chaps).

Now, the point is: she's not the slightest jealous of me. I don't know why (I believe she knows about my past and she surely see how I deal with women) but it's like she absolutely believes I would never ever cheat on her. For example, I planned to go to the seaside with some buddies last weekend and she was just "great, have fun!".

I know this is actually a perfect situation for me (I can get some on the side and she'd never know or doubt me) but I believe this relationship needs some changes in terms of who is in charge - she needs to be afraid of me leaving. What would be the best way to make a girl like this jealous out of her mind? I've flirted, with good results, with other girls honestly better looking than her in front of her eyes and she didn't even care. I need some heavy guns here.