It seems like a lot of people on Reddit in general think that guys don't like women who have casual sex but I think that's missing the point entirely. At least from my experience as a late-20s guy living in a big city, the vast majority of people (male or female) generally have a "history" consisting of a few flings and a serious relationship or two. Most guys are okay with dating a girl who has had a few flings in the past unless they're more on the conservative side.

Which brings me to my point... girls having casual sex as part of their history isn't the problem for guys. I've dated girls before who have definitely slept around in the past and I never cared, but that's because THEY ALSO HAD SLEPT WITH ME PRETTY EARLY ON. The problem is when a girl has had casual sex in the past and slept with guys early without any commitments but then makes her boyfriend wait and jump through all sorts of hoops for sex. It's like having to do multiple in-person interviews for a job on top of having a masters degree from a top school, 5 years of industry experience, etc and then finding out that your company hired your coworker who only has a bachelor's degree from a no-name school and only required him to do a 30 minute phone interview to get the position. It makes you feel like you're held to a significantly higher standard and that's what men aren't okay with.

It applies to both genders too, I'm sure most women wouldn't like being held to a higher standard either. Imagine if a girl meets a guy... he invites her over for Netflix n' Chill for 3 months while keeping their arrangement a secret before finally committing to her. She'd probably be pretty pissed if she found out that he had committed to his ex within a few weeks, was taking her out on nice dates, and introducing her to his friends early on while she had to wait around and jump through hoops waiting for his commitment.

Now this all isn't to say that if a girl slept with a guy on the night they met and it didn't work out, that she needs to sleep with every guy she meets on the first date moving forward. Just like if a guy once dropped $200 on a first date and got ghosted afterwards, he shouldn't spend that much money on the first date for every girl he meets. Overall I think that if someone wants to "wait", then they should just find someone who also wants to wait. That way no one's jumping through any hoops to get sex/commitment from the other and things progress more naturally.