Billy:
-Jason Todd/Robin
-you met at a Justice League meeting and Jason thought you were beautiful so he flirted with you
-Billy got jealous but he was in his hero form and no one knew he was a kid (except for Bruce) so he couldn't do anything
-you reassured him that it was fine and you loved only him but ever since then, every time you and Jason interact he gets jealous
Freddie:
-Billy Batson
-he knows Billy is your best friend but he still feels jealous of how close you are
-also he has a certain jealousy of Billy's appearance and "don't care attitude" that doesn't help when it comes to you