Is he cheating??

So today when I went to get inside my car and tried connecting my phone I notice my boyfriend had left his phone connected to the car already. The screen was on recent calls and I realized it was a girls name and if I kept scrolling there were more calls just from her. So then I decided to check his missed calls and his dialed calls and it’s literally all this chick. And when I asked him about it he claims she’s just a friend. But I have a hard time believing that just a friend calls you so much like that like his phone calls were literally all her. I have a gut feeling something is off. Apart from this text conversation he refuses to talk about it. And I know damn well if I had a guy “friend” calling me like that he’d loose it lol