Okay now after reading the thread, I'll make my point.
I won't say I never get jealous, but its a rarity. With that said, it normally takes specific things to make me jealous - you know the type of guy that you know she likes, just throwing himself at her and getting touchy feely - thats a no go. Any other guy she can flirt with and there's no problem.
Also when I was with the ex girlfriend, I knew she was always coming home with me so it was a non issue about her flirting with anyone. I would, however, get pissed when guys who constantly hit on her and expressed their feelings for her would try to move in. It wasn't that I didn't trust her, it was that I didn't trust them and I feared for my girl getting taken advantage of or sexually assaulted, and I feared that I would have to crack their skulls open.
The last time this happened she had told me this guy was giving her a hard time and throwing himself at her when I was away for the week, and then he wound up showing up at a party that we were at. Of course he was as sweet as pie and sat there with his mouth shut, so he didn't get himself in trouble. Haha @ his silence that night pissing me off very badly since I was toasted. He wound up walking halfway home with us before saying goodbye and since I was drunk and he was behind me with my girl he tried to get touchy feely. I won't forget the look on his face as I cracked that lightpole rather than him and he took off in the other direction.