In a sane world, if you had a gf, you would be outraged if another man had sex with her. However, in porn, you are watching a woman that you'd have as a gf (at least if you were single) be fucked by another man, and you are getting off on her being fucked by another man or her sucking off another man. That is the definition of being a cuckold-getting off of your woman having sexual relations with another man right in your sight. At the very least, porn trains men to be cucks or to ingrain that fetish into otherwise normal men.
It also can make otherwise good young men into creepy voyeurs, which at worst, can be a crime. It instills the pleasures of watching couples have sex while they don't know you're around, turning you into some creepy "watcher," and it's normalized being a "watcher."
Even "straight" porn could be considered gay if you get excited or feel positive when you see the man's dick as he's about to plow a girl. I've heard that some gay men enjoy seeing straight men fuck women because they like seeing men in action, not caring about the woman, of course.
If you think about it, porn is kinda fucked up, at least if it isn't a nude woman or man (whatever you're into) because being nude, they're single, but porn is like a drug so a nude adult of choice wasn't enough, so they had to go into more hardcore fetishes, mirroring getting into more hardcore drugs.
Porn fries your frontal lobe and re-programs how your sex drive works. Over time, you calibrate your tastes to fit the sexual stimuli. In a sane world, your sex drive/sexual appetite would be informed by how you interact sexually with your wife/gf.
The porn industry is built on sex trafficking. For every woman who "enjoys" being involved in it, there are hundreds more who are being trafficked. Pornhub stepped back from "amateur" videos for this reason, not because they care, but because they were being investigated for hosting child pornography, which they were.
For the record, all porn is child porn. At what age is it acceptable for your daughter to become a whore? Pornography is a weapon of war. Don't let it consume you.