Boyfriends and Snapchat

So my boyfriend of a year has recently started snapchatting this 22 yo girl every day for the past 13 days, he's almost 31. They just met maybe a month ago she works at the bar he works at. Him and his friends have called her hot and even used the word bonerific. I told him I'm not comfortable with it but he still does it. He says it's nothing but it still bugs me. We also just got back togerher after taking a week break. What should I do?