Eren :

You were talking to Armin about the outside world and Eren didn't like it one bit , He got jealous really easily but he knows you'd never cheat but its the boys he doesn't trust . So he tried to get your attention

"(Y/n) , (Y/n) listin to me " eren whined
"One minute eren , Armin telling me about the ocean " you say

He the picks up over his shoulder and walks way with you , leaving a confused armin behind

Armin

He doesn't get jealous because he trusts you but when he did , he would think the guy is try to take you way form him so he kisses your cheek or hold your hand in front of the boy until he walks away

Levi :

He will glare at the person your hanging out with , and threaten him without you knowing

Jean :

Jean gets jealous easily like eren but he stays by your side to make sure the guy your hanging out with isnt doing anything to you