I think it would depend on who is approaching/flirting with Connor. I don't really plan to have anyone be possessive of him, but they might be annoyed if it's, like, their worst enemy trying to take their man.
Maybe Matt would be the most prone to jealousy just because he's used to being Connor's top priority, but honestly, that envy is often quickly replaced with arousal. He's thinking something like "Ugh, why is Connor spending all his time with his roommate and not me! Wait, maybe the three of us could hang out together... 😈"