my boyfriend keeps having wet dreams about other women

it’s so bad that whenever he dreams it’s just about some other girl . it makes me feel terrible because last night he was having an orgy & he came all over the bed . i wasn’t part of it , i know he cant control it but what is causing these dreams makes me angry & sad . thoughts ? our sex life is active for the most part . once i gave him head & he fell asleep , he woke up & told me he fucked a bitch that wasn’t me in his sleep so it’s not because we aren’t sexually actively