I'd get it if Ishid was jealous over another guy flirting with Yunifer, but in this case he's just being petty. So she can't have friends? Wtf is up with that? Irl this would be a huge red flag.
I honestly feel bad for Rael. She's never done anything wrong and she just wants to be friends. I get why Yunifer keeps rejecting her friendship, but Rael has no clue. Ofc, the 'stalking' is a bit creepy, but I don't think she's nearly as possessive as Ishid.