I think most are over-analyzing the photo shoot with Erynn.
Maybe if you have given Lexi reason to be jealous of the interactions with Erynn up to that point, and we know Layla gets worked up easily because of her insecurities/inexperience, but even then they both know the MC is close to Erynn(are friends at least.)
Nikki may show the most jealousy because she's already met Erynn and had the in-bed catfight (which - god, I wish we could get more of that. Nikki is at her most sexy when physically assaulting the other LI's!). I think that would be the biggest reaction.
Elena - would say 'dios mio' and move past it.
Iris - would probably be jealous and look to pursue a threesome.
Mira (if she jumps into the game as a real LI) - isn't coming to Madison Springs at the moment, so don't see it.
Valeria - would just be like, 'ok' and just go with the flow. super low-key.
Cara - cant speak to, I've never really gone far down that path.
Gabi - can be jealous, but she's not saying anything in public.
Anyone else would be after the photo shoot and it wouldn't be a thing.