He lied to me about something so simple?

My boyfriend is friends with a girl who's also my friend. I don't care since I trust the both of them, but he tells me they barely text each other. I was talking to her today, and she was talking about all the funny stuff he said and even went on a little rant on how he doesn't know what Rocky Horror Show is. She showed me the texts they had because "look how dumb your boyfriend is" 😂
She said that they text all the time and that she doesn't understand how I can deal with him. I don't think they're up to anything, but why would my boyfriend lie about something so small like that? I'm not mad, but I'm confused.