Boyfriend going to prom with another girl

So am I over reacting or no? So my boyfriend told me today that he’s going to prom with his friend that’s a girl, he’s a junior and she’s a senior. She asked him to go with her to prom. I’m like fucking pissed wtf is he going to prom with another girl for and the girl obviously likes him but he claims that she doesn’t. I’m a female I know how a female acts when they like someone and it’s so fucking obvious that she likes him. She’s always posting photos of him and her on her Facebook also which fucking pisses me off. I told my boyfriend something and his reply was, “she doesn’t like me she likes black boys.” Mhmmm yeah ok. He doesn’t get it he’s like big deal I’m going to prom but like wtf does he need to go to prom for but he didn’t even want to go to junior banquet which he can actually take me to. His excuse was “oh I went to jb last year I don’t want to go this year.” So what next year when prom comes he’s going to say the same shit. Btw we go to different high schools.