is he hiding something?

okay so me and my boyfriend have been dating for about a year & a half. ive also had this best friend and we all the used to talk a lot but i lost touch with my best friend. Today she messaged me and told me to get on her instagram account to message someone on direct message. when i got on, i seen where it said her and my boyfriend were talking 10 hours ago. when i clicked on it, it was only showing messages from months ago. did they delete their messages or something? he's messaged one of my old friends before when we got in an argument and tried to hide it. he even wanted to have a threesome with my friend that he was apparently messaging 10 hours ago. do you think they're hiding something? i'm so nervous.