There is two types of color blending, tint and light.
Tint is what is usually taught, primaries are red, blue,yellow and we make the rest with them.
With light however, the primaries are Red, Blue and Green. Most image editing software use light blending, so you can zoom on a pixel and use a color picker to get its RGB value. And to make yellow with light blending, you combine red and green
Extra fun fact! Tint primaries are actually Magenta, Yellow, and Cyan.
Red + Blue = Magenta Red + Green = Yellow Green + Blue = Cyan
Magenta + Yellow = Red Magenta + Cyan = Blue Cyan + Yellow = Green
It may not be realistic, but wouldn't it be cooler if it did?
Like, seriously, nobody question when a character breaks physics when they flash step, shoot laser beams, or fly solely by their willpower.
Why should porn be subjected to realism more than non porn?