/cgl/ - Cosplay & EGL

my ex- fwb is now in a relationship with someone for over a year now but he wanted to threesome with me and so we did, that was a couple months ago and he said he and his gf want to again, which im excited since it went so well but then he started mentioning other possible options of who else they would threesome instead and im suddenly all jealous over the fact that im not their only option ? Why the fuck do i get so pissed about it