does my girlfriend want to go black?

i've been dating her for about three years now and i am the only guy she's ever had sex with, unless she's cheating on me which is possible but it doesn't seem like she is. i know she is not satisfied with my 5-inch cock, she often asks me if i'm inside her when i'm as deep as i can go and will tell me to go deeper when i'm already straining to get as deep as i can. she's also subtly complained about my size and has even asked me if my cock was shrinking before. when i mentioned a cock extension sleeve once she half-joked that i should get one. the point is she is not satisfied with my small white cock and the fact that i'm lucky if i get her panties off once every couple weeks is proof enough of that.

she claims she isn't attracted to black guys but i know she had huge schoolgirl crushes on lots of black basketball players and rappers before we started dating. and if we're watching porn and there's a black guy in it she'll act disinterested at first but will start talking about his cock ("it's so thick" "that's more than twice as big as yours") and by the end she'll be dripping wet, she once even complained about how wet she was because her pussy was literally dripping onto my bedsheets (and she has a very nice, tight pussy by the way). if we're watching porn clips on the internet towards the end of it she'll have me looking up black on white gangbangs and will be horny to the point that i have no chance of satisfying her.

so i think the answer to my question is obvious, she craves black cock. but she will only joke about wanting it and will not seriously admit that she actually wants to be with a black guy. how can i get her to go black?