I don’t truly understand how this works…(NSFW)

I know I am a Christian, I was baptized in my teens. I know that we as Christians are supposed to be careful not to sin, but as humans, we sin every day, atleast unintentionally. I am 3 weeks clean from porn, but…this is the part i genuinely don’t understand, why would God give us genitalia but expect us to not masterbate to release stress or just because it feels good…why does he get mad at us?