Why do girls care if guys watch pron?

Beyond caring it seems to really bother a lot of women. And I get the jealousy part of it. I also don't think it's fair to the women if they're sexually available for and totally exclusive with the man they're with. But the problem is neither of those things are usually the case in relationships nowadays. And it's even worse imo for women to be complaining about what stranger men are doing with their bodies by themselves, because 9.9 times out of 10 these women have their own sexual history on top of using pron/erotica or toys. It's just extremely ironic to me for them to attempt judging or looking down on men for something like this when all things are considered.