My boyfriend is jealous but never admits it

My boyfriend thinks i like my friend in my business class and history class. Just because we talk as friends doesn’t mean i like him! I’ve noticed that if I talk to him, my boyfriend will message me later that evening saying that i flirt with him and stuff. Even if we have a small friendly conversation on snapchat, my boyfriend will try to look through my phone and see the messages with my friend. I tell my boyfriend that he’s jealous and theres no need to be because I don’t flirt or fancy my friend 😂 but ofc he denies it