I can't relate to this mentality at all any more. I was monogamous for a long time but chose polyamory ten years ago this week. My partners and I enthusiastically support one another in our other relationships. My girlfriend and I were at a show on a date last year, and she was like "Omfg, that bartender is so fucking hot...". I pumped her up, and she gave the bartender her number.

I honestly don't remember what relationship jealousy feels like any more. When my partner is excited about someone new, I squee the fuck out for them.