engaged but so turned on by strangers

i'm engaged to this amazing guy, we've been together since college and he's the best. i know it might sound weird, but lately i've had these crazy fantasies about guys i don't even know. like walking down the street and seeing some hot stranger, and just wanting him so bad. it's not like i want to cheat or anything, i still love my fiancé way too much for that. but there's this weird excitement in knowing i could make eyes at a total stranger, have sex with them, and never see them again. just anonymous hookups for the thrill of it. last week i got super turned on seeing some guy in his early thirties, kinda nerdy glasses and longish brown hair. i wanted him so bad, imagined us getting into his car right there and driving to this random hotel, having crazy intense sex all night. when my fiancé came home from work and saw me, we had our usual bedtime routine but i just kept thinking about that stranger the whole time. i felt kinda guilty afterwards but also like it was one of the hottest moments ever. now anytime we're in public or out at a bar i'm super paranoid that something will set off these wild fantasies again. i hope my fiancé never finds this post because honestly i think he'd be really hurt by how turned on i get by random guys sometimes even if they're just figments of my imagination.